Tootfinder

US Treasury says threat to sanction 3rd-country banks has impacted Russian funding flows: https://benborges.xyz/2024/02/26/us-treasury-says.html

Uncertainties in Measurements of Bubbly Flows Using Phase-Detection Probes
Matthias B\"urgler, Daniel Valero, Benjamin Hohermuth, Robert M. Boes, David F. Vetsch
https://arxiv.org/abs/2403.16091

Uncertainties in Measurements of Bubbly Flows Using Phase-Detection Probes
The analysis of bubbly two-phase flows is challenging due to their turbulent nature and the need for intrusive phase-detection probes. However, accurately characterizing these flows is crucial for safely designing critical infrastructure such as dams and their appurtenant structures. The combination of dual-tip intrusive phase-detection probes with advanced signal processing algorithms enables the assessment of pseudo-instantaneous 1-D velocity time series; for which the limitations are not ful…

Obstructing Anosov flows on cusped 3-manifolds
Misha Schmalian
https://arxiv.org/abs/2403.17060 https://arxiv.org/pdf/2403.17060

Obstructing Anosov flows on cusped 3-manifolds
Using results relating taut foliations and pseudo-Anosov flows, we find cusped hyperbolic 3-manifolds which are not the non-singular part of a pseudo-Anosov flow. In particular, we find the first examples of cusped hyperbolic 3-manifolds not admitting veering triangulations, confirming a conjecture of S. Schleimer.

Contribution of neutrino-dominated accretion flows to cosmic MeV neutrino background
Yun-Feng Wei, Tong Liu, Cui-Ying Song
https://arxiv.org/abs/2403.16856

Contribution of neutrino-dominated accretion flows to cosmic MeV neutrino background
Neutrino-dominated accretion flows (NDAFs) are one of the important MeV neutrino sources and significantly contribute to the cosmic diffuse neutrino background. In this paper, we investigate the spectrum of diffuse NDAF neutrino background (DNNB) by fully considering the effects of the progenitor properties and initial explosion energies based on core-collapse supernova (CCSN) simulations, and estimate the detectable event rate by Super-Kamiokande detector. We find that the predicted background…

Performance of high-order Godunov-type methods in simulations of astrophysical low Mach number flows
G. Leidi, R. Andrassy, W. Barsukow, J. Higl, P. V. F. Edelmann, F. K. R\"opke
https://arxiv.org/abs/2402.16706

Performance of high-order Godunov-type methods in simulations of astrophysical low Mach number flows
High-order Godunov methods for gas dynamics have become a standard tool for simulating different classes of astrophysical flows. Their accuracy is mostly determined by the spatial interpolant used to reconstruct the pair of Riemann states at cell interfaces and by the Riemann solver that computes the interface fluxes. In most Godunov-type methods, these two steps can be treated independently, so that many different schemes can in principle be built from the same numerical framework. In this wor…

This https://arxiv.org/abs/2402.02266 has been replaced.
link: https://scholar.google.com/scholar?q=a

On asymptotic expansions of ergodic integrals for $\Z^d$-extensions of translation flows
We obtain expansions of ergodic integrals for $\Z^d$-covers of compact self-similar translation flows, and as a consequence we obtain a form of weak rational ergodicity with optimal rates. As examples, we consider the so-called self-similar $(s,1)$-staircase flows ($\Z$-extensions of self-similar translations flows of genus-$2$ surfaces), and a variation of the Ehrenfest wind-tree model.

On three dimensional flows of viscoelastic fluids of Giesekus type
Miroslav Bul\'i\v{c}ek, Tom\'a\v{s} Los, Josef M\'alek
https://arxiv.org/abs/2403.17348

On three dimensional flows of viscoelastic fluids of Giesekus type
Viscoelastic rate-type fluids are popular models of choice in many applications involving flows of fluid-like materials with complex micro-structure. A well-developed mathematical theory for the most of these classical fluid models is however missing. The main purpose of this study is to provide a complete proof of long-time and large-data existence of weak solutions to unsteady internal three-dimensional flows of Giesekus fluids subject to a no-slip boundary condition. As a new auxiliary tool,…

Hey friends! I finally wrote about my second attempt to get a #photo of the frozen #waterfall
Unfortunately, it wasn't THAT frozen anymore - but ... wasn't it even better?! I wrote down the story in my blog and this time I also uploaded the photo to FineArtsAmerica if you think about …

Frozen by Franz Graf
Frozen Photograph by Franz Graf

Numerical Analysis on Neural Network Projected Schemes for Approximating One Dimensional Wasserstein Gradient Flows
Xinzhe Zuo, Jiaxi Zhao, Shu Liu, Stanley Osher, Wuchen Li
https://arxiv.org/abs/2402.16821

Numerical Analysis on Neural Network Projected Schemes for Approximating One Dimensional Wasserstein Gradient Flows
We provide a numerical analysis and computation of neural network projected schemes for approximating one dimensional Wasserstein gradient flows. We approximate the Lagrangian mapping functions of gradient flows by the class of two-layer neural network functions with ReLU (rectified linear unit) activation functions. The numerical scheme is based on a projected gradient method, namely the Wasserstein natural gradient, where the projection is constructed from the $L^2$ mapping spaces onto the ne…

Flows of Local Sheet Dwarfs in Relation to the Council of Giants
L. M. SeatonYork University, Canada, M. L. McCallYork University, Canada, N. T. McCallYork University, Canada
https://arxiv.org/abs/2402.15711

Flows of Local Sheet Dwarfs in Relation to the Council of Giants
The kinematics of isolated dwarf galaxies in the Local Sheet have been studied to ascertain how the Council of Giants has affected flows. Peculiar velocities parallel to the Sheet in the frame of reference of the Council ascend steeply from negative to positive values on the near side of the Council at a heliocentric radius of $2.4 \pm 0.2$ Mpc. They descend to preponderantly negative values at a radius of $3.9^{+0.4}_{-0.5}$ Mpc, which is near the middle of the Council realm. Such behaviour is…

This https://arxiv.org/abs/2202.05650 has been replaced.
link: https://scholar.google.com/scholar?q=a

Bernstein Flows for Flexible Posteriors in Variational Bayes
Variational inference (VI) is a technique to approximate difficult to compute posteriors by optimization. In contrast to MCMC, VI scales to many observations. In the case of complex posteriors, however, state-of-the-art VI approaches often yield unsatisfactory posterior approximations. This paper presents Bernstein flow variational inference (BF-VI), a robust and easy-to-use method, flexible enough to approximate complex multivariate posteriors. BF-VI combines ideas from normalizing flows and B…

Parallel Approximate Maximum Flows in Near-Linear Work and Polylogarithmic Depth
Arpit Agarwal, Sanjeev Khanna, Huan Li, Prathamesh Patil, Chen Wang, Nathan White, Peilin Zhong
https://arxiv.org/abs/2402.14950

Parallel Approximate Maximum Flows in Near-Linear Work and Polylogarithmic Depth
We present a parallel algorithm for the $(1-ε)$-approximate maximum flow problem in capacitated, undirected graphs with $n$ vertices and $m$ edges, achieving $O(ε^{-3}\text{polylog} n)$ depth and $O(m ε^{-3} \text{polylog} n)$ work in the PRAM model. Although near-linear time sequential algorithms for this problem have been known for almost a decade, no parallel algorithms that simultaneously achieved polylogarithmic depth and near-linear work were known. At the heart of our result is a po…

Big money flows to US charities fueling vaccine misinformation
https://www.yahoo.com/news/big-money-flows-us-charities-012855095.html

Big money flows to US charities fueling vaccine misinformation
An anti-vaccine group founded by US presidential contender Robert F. Kennedy Jr raised millions of dollars during the coronavirus pandemic, tax records show,...

Optimal control of gradient flows via the Weighted Energy-Dissipation method
Takeshi Fukao, Ulisse Stefanelli, Riccardo Voso
https://arxiv.org/abs/2403.15055

Optimal control of gradient flows via the Weighted Energy-Dissipation method
We consider a general optimal control problem in the setting of gradient flows. Two approximations of the problem are presented, both relying on the variational reformulation of gradient-flow dynamics via the Weighted-Energy-Dissipation variational approach. This consists in the minimization of global-in-time functionals over trajectories, combined with a limit passage. We show that the original nonpenalized problem and the two successive approximations admits solutions. Moreover, resorting to …

Classification of connected \'etale algebras in multiplicity-free modular fusion categories up to rank nine
Ken Kikuchi
https://arxiv.org/abs/2404.16125

Classification of connected étale algebras in multiplicity-free modular fusion categories up to rank nine
We classify connected étale algebras $A$'s in multiplicity-free modular fusion categories $\mathcal B$'s with $\text{rank}(\mathcal B)\le9$. We also identify categories $\mathcal B_A$'s of right $A$-modules. The results have physical applications in constraining renormalization group flows. As demonstration, we study massive renormalization group flows from non-unitary minimal models to predict ground state degeneracies and prove spontaneous $\mathcal B$-symmetry breaking.

This https://arxiv.org/abs/2401.05029 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_mat…

Smooth axisymmetric transonic irrotational flows to the steady Euler equations with an external force
For a class of external forces, we prove the existence and uniqueness of smooth transonic flows to the one dimensional steady Euler system with an external force, which is subsonic at the inlet and flows out at supersonic speed after smoothly accelerating through the sonic point. We then investigate the structural stability of the one-dimensional smooth transonic flows with positive acceleration under axisymmetric perturbations of suitable boundary conditions, and establish the first existence …

Entropy-conservative high-order methods for high-enthalpy gas flows
Georgii Oblapenko, Manuel Torrilhon
https://arxiv.org/abs/2403.16882 https://

Entropy-conservative high-order methods for high-enthalpy gas flows
A framework for numerical evaluation of entropy-conservative volume fluxes in gas flows with internal energies is developed, for use with high-order discretization methods. The novelty of the approach lies in the ability to use arbitrary expressions for the internal degrees of freedom of the constituent gas species. The developed approach is implemented in an open-source discontinuous Galerkin code for solving hyperbolic equations. Numerical simulations are carried out for several model 2-D flo…

SKdV, SmKdV flows and their supersymmetric gauge-Miura transformations
Y. F. Adans, A. R. Aguirre, J. F. Gomes, G. V. Lobo, A. H. Zimerman
https://arxiv.org/abs/2403.16285

SKdV, SmKdV flows and their supersymmetric gauge-Miura transformations
The construction of Integrable Hierarchies in terms of zero curvature representation provides a systematic construction for a series of integrable non-linear evolution equations (flows) which shares a common affine Lie algebraic structure. The integrable hierarchies are then classified in terms of a decomposition of the underlying affine Lie algebra $\hat \lie $ into graded subspaces defined by a grading operator $Q$. In this paper we shall discuss explicitly the simplest case of the affine $\h…

This https://arxiv.org/abs/2312.05264 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_csCR_…

All Rivers Run to the Sea: Private Learning with Asymmetric Flows
Data privacy is of great concern in cloud machine-learning service platforms, when sensitive data are exposed to service providers. While private computing environments (e.g., secure enclaves), and cryptographic approaches (e.g., homomorphic encryption) provide strong privacy protection, their computing performance still falls short compared to cloud GPUs. To achieve privacy protection with high computing performance, we propose Delta, a new private training and inference framework, with compar…

Numerical Analysis on Neural Network Projected Schemes for Approximating One Dimensional Wasserstein Gradient Flows
Xinzhe Zuo, Jiaxi Zhao, Shu Liu, Stanley Osher, Wuchen Li
https://arxiv.org/abs/2402.16821

Numerical Analysis on Neural Network Projected Schemes for Approximating One Dimensional Wasserstein Gradient Flows
We provide a numerical analysis and computation of neural network projected schemes for approximating one dimensional Wasserstein gradient flows. We approximate the Lagrangian mapping functions of gradient flows by the class of two-layer neural network functions with ReLU (rectified linear unit) activation functions. The numerical scheme is based on a projected gradient method, namely the Wasserstein natural gradient, where the projection is constructed from the $L^2$ mapping spaces onto the ne…

This https://arxiv.org/abs/2312.09784 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_qu…

Quantum Algorithm for Solving the Advection Equation using Hamiltonian Simulation
A quantum algorithm for solving the advection equation by embedding the discrete time-marching operator into Hamiltonian simulations is presented. One-dimensional advection can be simulated directly since the central finite difference operator for first-order derivatives is anti-Hermitian. Here, this is extended to industrially relevant, multi-dimensional flows with realistic boundary conditions and arbitrary finite difference stencils. A single copy of the initial quantum state is required and…

This https://arxiv.org/abs/2209.13272 has been replaced.
link: https://scholar.google.com/scholar?q=a

Tangential Tensor Fields on Deformable Surfaces -- How to Derive Consistent $L^2$-Gradient Flows
We consider gradient flows of surface energies which depend on the surface by a parameterization and on a tangential tensor field. The flow allows for dissipation by evolving the parameterization and the tensor field simultaneously. This requires the choice of a notation for independence. We introduce different gauges of surface independence and show their consequences for the evolution. In order to guarantee a decrease in energy, the gauge of surface independence and the time derivative have t…

Towards Mixed Reality as the Everyday Computing Paradigm: Challenges & Design Recommendations
Amir Reza Asadi, Reza Hemadi
https://arxiv.org/abs/2402.15974

Towards Mixed Reality as the Everyday Computing Paradigm: Challenges & Design Recommendations
This research presents a proof-of-concept prototype of an all-in-one mixed reality application platform, developed to investigate the needs and expectations of users from mixed reality systems. The study involved an extensive user study with 1,052 participants, including the collection of diaries from 6 users and conducting interviews with 51 participants to gain deeper insights into their experiences. The findings from the interviews revealed that directly porting current user flows into 3D en…

This https://arxiv.org/abs/2207.14016 has been replaced.
link: https://scholar.google.com/scholar?q=a

Cascades towards noise-induced transitions on networks revealed using information flows
The success of clandestine organizations require novel methods to improve methods of intervention for law enforcement agencies. Through a model rooted in evolutionary game theory, we present an approach to conceptualize criminal organizations as collaborative assemblies of roles. The model explores decision-making processes within these organizations, considering factors such as expected costs, potential benefits, and the certainty of expected payouts. Key findings include the identification of…

Parallel Approximate Maximum Flows in Near-Linear Work and Polylogarithmic Depth
Arpit Agarwal, Sanjeev Khanna, Huan Li, Prathamesh Patil, Chen Wang, Nathan White, Peilin Zhong
https://arxiv.org/abs/2402.14950

Parallel Approximate Maximum Flows in Near-Linear Work and Polylogarithmic Depth
We present a parallel algorithm for the $(1-ε)$-approximate maximum flow problem in capacitated, undirected graphs with $n$ vertices and $m$ edges, achieving $O(ε^{-3}\text{polylog} n)$ depth and $O(m ε^{-3} \text{polylog} n)$ work in the PRAM model. Although near-linear time sequential algorithms for this problem have been known for almost a decade, no parallel algorithms that simultaneously achieved polylogarithmic depth and near-linear work were known. At the heart of our result is a po…

Hybrid Physics-Based and Data-Driven Modeling of Vascular Bifurcation Pressure Differences
Natalia L. Rubio, Luca Pegolotti, Martin R. Pfaller, Eric F. Darve, Alison L. Marsden
https://arxiv.org/abs/2402.15651 https://arxiv.org/pdf/2402.15651
arXiv:2402.15651v1 Announce Type: new
Abstract: Reduced-order models (ROMs) allow for the simulation of blood flow in patient-specific vasculatures without the high computational cost and wait time associated with traditional computational fluid dynamics (CFD) models. Unfortunately, due to the simplifications made in their formulations, ROMs can suffer from significantly reduced accuracy. One common simplifying assumption is the continuity of static or total pressure over vascular junctions. In many cases, this assumption has been shown to introduce significant error. We propose a model to account for this pressure difference, with the ultimate goal of increasing the accuracy of cardiovascular ROMs. Our model successfully uses a structure common in existing ROMs in conjunction with machine-learning techniques to predict the pressure difference over a vascular bifurcation. We analyze the performance of our model on steady and transient flows, testing it on three bifurcation cohorts representing three different bifurcation geometric types. We also compare the efficacy of different machine-learning techniques and two different model modalities.

This https://arxiv.org/abs/2107.11246 has been replaced.
link: https://scholar.google.com/scholar?q=a

Chance Constrained Economic Dispatch Considering the Capability of Network Flexibility Against Renewable Uncertainties
This paper incorporates a continuous-type network flexibility into chance constrained economic dispatch (CCED). In the proposed model, both power generations and line susceptances are continuous variables to minimize the expected generation cost and guarantee a low probability of constraint violation in terms of generations and line flows under renewable uncertainties. From the analytical form of CCED, we figure out the mechanism of network flexibility against uncertainties -- while renewable u…

Mean temperature and concentration profiles in turbulent internal flows
Sergio Pirozzoli, Davide Modesti
https://arxiv.org/abs/2403.17689 https://

Mean temperature and concentration profiles in turbulent internal flows
We derive explicit formulas for the mean profiles of temperature or concentration of a diffusing substance (modeled as passive scalars) in forced turbulent convection, as a function of the Reynolds and Prandtl numbers. The derivation leverages on the observed universality of the inner-layer thermal eddy diffusivity with respect to Reynolds and Prandtl number variations and across different flows, and on universality of the passive scalar defect in the core flow. Matching of the inner- and outer…

Two-dimensional jet flows for compressible full Euler system with general vorticity
Yan Li
https://arxiv.org/abs/2404.16377 https://a…

Two-dimensional jet flows for compressible full Euler system with general vorticity
In this paper, we consider the well-posedness theory of two-dimensional compressible subsonic jet flows for steady full Euler system with general vorticity. Inspired by the analysis in arXiv:2006.05672, we show that the stream function formulation for such system admits a variational structure. Then the existence and uniqueness of a smooth subsonic jet flow can be established by the variational method developed by Alt, Caffarelli and Friedman. Furthermore, the far fields behavior of the flow an…

This https://arxiv.org/abs/2009.13607 has been replaced.
link: https://scholar.google.com/scholar?q=a

Modulus of continuity for spectral measures of suspension flows over Salem type substitutions
We study the spectrum of the self-similar suspension flows of sub-shifts arising from primitive substitutions. We focus on the case where the substitution matrix has a Salem number α as dominant eigenvalue. We obtain a Hölder exponent for the spectral measures for points away from zero and belonging to the field Q(α). This exponent depends only on three parameters of each of these points: its absolute value, the absolute value of its real conjugate and its denominator.

This https://arxiv.org/abs/2401.13966 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_mat…

The Avoidance Principle for Noncompact Hypersurfaces Moving by Mean Curvature Flow
Consider a pair of smooth, possibly noncompact, properly immersed hypersurfaces moving by mean curvature flow, or, more generally, a pair of weak set flows. We prove that if the ambient space is Euclidean space and if the distance between the two surfaces is initially nonzero, then the surfaces remain disjoint at all subsequent times. We prove the same result when the ambient space is a complete Riemannian manifold of nonzero injectivity radius, provided the curvature tensor (of the ambient spa…

Improving $\Lambda$ Signal Extraction with Domain Adaptation via Normalizing Flows
Rowan Kelleher, Matthew McEneaney, Anselm Vossen
https://arxiv.org/abs/2403.14076

Improving $Λ$ Signal Extraction with Domain Adaptation via Normalizing Flows
The present study presents a novel application for normalizing flows for domain adaptation. The study investigates the ability of flow based neural networks to improve signal extraction of $Λ$ Hyperons at CLAS12. Normalizing Flows can help model complex probability density functions that describe physics processes, enabling uses such as event generation. $Λ$ signal extraction has been improved through the use of classifier networks, but differences in simulation and data domains limit classif…

Mean temperature and concentration profiles in turbulent internal flows
Sergio Pirozzoli, Davide Modesti
https://arxiv.org/abs/2403.17689 https://

Mean temperature and concentration profiles in turbulent internal flows
We derive explicit formulas for the mean profiles of temperature or concentration of a diffusing substance (modeled as passive scalars) in forced turbulent convection, as a function of the Reynolds and Prandtl numbers. The derivation leverages on the observed universality of the inner-layer thermal eddy diffusivity with respect to Reynolds and Prandtl number variations and across different flows, and on universality of the passive scalar defect in the core flow. Matching of the inner- and outer…

Higher-Order Energy-Decreasing Exponential Time Differencing Runge-Kutta methods for Gradient Flows
Zhaohui Fu, Jie Shen, Jiang Yang
https://arxiv.org/abs/2402.15142

Higher-Order Energy-Decreasing Exponential Time Differencing Runge-Kutta methods for Gradient Flows
In this paper, we develop a general framework for constructing higher-order, unconditionally energy-stable exponential time differencing Runge-Kutta methods applicable to a range of gradient flows. Specifically, we identify conditions sufficient for ETDRK schemes to maintain the original energy dissipation. Our analysis reveals that commonly used third-order and fourth-order ETDRK schemes fail to meet these conditions. To address this, we introduce new third-order ETDRK schemes, designed with a…

This https://arxiv.org/abs/2310.17543 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_mat…

On invariant distributions of Feller Markov chains with applications to dynamical systems with random switching
We introduce simple conditions ensuring that invariant distributions of a Feller Markov chain on a compact Riemannian manifold are absolutely continuous with a lower semi-continuous, continuous or smooth density with respect to the Riemannian measure. This is applied to Markov chains obtained by random composition of maps and to piecewise deterministic Markov processes obtained by random switching between flows.

GAL{\AE}XI: Solving complex compressible flows with high-order discontinuous Galerkin methods on accelerator-based systems
Daniel Kempf, Marius Kurz, Marcel Blind, Patrick Kopper, Philipp Offenh\"auser, Anna Schwarz, Spencer Starr, Jens Keim, Andrea Beck
https://arxiv.org/abs/2404.12703…

GALÆXI: Solving complex compressible flows with high-order discontinuous Galerkin methods on accelerator-based systems
This work presents GALÆXI as a novel, energy-efficient flow solver for the simulation of compressible flows on unstructured meshes leveraging the parallel computing power of modern Graphics Processing Units (GPUs). GALÆXI implements the high-order Discontinuous Galerkin Spectral Element Method (DGSEM) using shock capturing with a finite-volume subcell approach to ensure the stability of the high-order scheme near shocks. This work provides details on the general code design, the parallelizati…

Stable Training of Normalizing Flows for High-dimensional Variational Inference
Daniel Andrade
https://arxiv.org/abs/2402.16408 https://

This https://arxiv.org/abs/2403.08216 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_csLG_…

PaddingFlow: Improving Normalizing Flows with Padding-Dimensional Noise
Normalizing flow is a generative modeling approach with efficient sampling. However, Flow-based models suffer two issues: 1) If the target distribution is manifold, due to the unmatch between the dimensions of the latent target distribution and the data distribution, flow-based models might perform badly. 2) Discrete data might make flow-based models collapse into a degenerate mixture of point masses. To sidestep such two issues, we propose PaddingFlow, a novel dequantization method, which impr…

This https://arxiv.org/abs/2103.01325 has been replaced.
link: https://scholar.google.com/scholar?q=a

Reeb flows transverse to foliations
Let $\mathcal F$ be a co-oriented $C^2$ foliation on a closed, oriented 3-manifold. We show that $T\mathcal F$ can be perturbed to a contact structure with Reeb flow transverse to $\mathcal F$ if and only if $\mathcal F$ does not support an invariant transverse measure. The resulting Reeb flow has no contractible orbits. This answers a question of Colin and Honda. The main technical tool in our proof is leafwise Brownian motion which we use to construct good transverse measures for $\mathcal F$…

This https://arxiv.org/abs/2403.04835 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_hept…

Non-Invertible Symmetries, Anomalies and Scattering Amplitudes
We show that crossing symmetry of S-matrices is modified in certain theories with non-invertible symmetries or anomalies. Focusing on integrable flows to gapped phases in two dimensions, we find that S-matrices derived previously from the bootstrap approach are incompatible with non-invertible symmetries along the flow. We present consistent alternatives, which however violate standard crossing symmetry and obey modified rules dictated by fusion categories. We extend these rules to theories wit…

Three-dimensional clustering characteristics of large-stokes number sprays interacting with turbulent swirling co-flows
Ali Rostami, Ri Li, Sina Kheirkhah
https://arxiv.org/abs/2403.15945

Three-dimensional clustering characteristics of large-stokes number sprays interacting with turbulent swirling co-flows
Three-dimensional (3D) clustering characteristics of large-stokes number sprays interacting with turbulent swirling co-flows are investigated experimentally. The Astigmatic Interferometric Particle Imaging (AIPI) technique is utilized for simultaneous measurement of the spray droplets position in 3D space and their corresponding diameter. The Stokes number estimated based on the Kolmogorov time scale varies from 34 to 142. The results show that the degree of droplet clustering plateaus at about…

Accretion tori around rotating neutron stars -- Paper II: Oscillations and precessions
Monika Matuszkov\'a, Gabriel T\"or\"ok, Kate\v{r}ina Klimovi\v{c}ov\'a, Ji\v{r}\'i Hor\'ak, Odele Straub, Eva \v{S}r\'amkov\'a, Debora Lan\v{c}ov\'a, Martin Urbanec, Gabriela Urbancov\'a, Vladim\'ir Karas
https://

Accretion tori around rotating neutron stars -- Paper II: Oscillations and precessions
The four characteristic oscillation frequencies of accretion flows are, in addition to the Keplerian orbital frequency, often discussed in the context of the time variability of the black hole and neutron star (NS) low-mass X-ray binaries (LMXBs). These are namely the frequencies of the axisymmetric radial and vertical epicyclic oscillations, and the frequencies of non-axisymmetric oscillations corresponding to the periastron (radial) and Lense-Thirring (vertical) precessions. In this context, …

Helioseismic Properties of Dynamo Waves in the Variation of Solar Differential Rotation
Krishnendu Mandal, Alexander G. Kosovichev, Valery V. Pipin
https://arxiv.org/abs/2402.15647

Helioseismic Properties of Dynamo Waves in the Variation of Solar Differential Rotation
Solar differential rotation exhibits a prominent feature: its cyclic variations over the solar cycle, referred to as zonal flows or torsional oscillations, are observed throughout the convection zone. Given the challenge of measuring magnetic fields in subsurface layers, understanding deep torsional oscillations becomes pivotal in deciphering the underlying solar dynamo mechanism. In this study, we address the critical question of identifying specific signatures within helioseismic frequency-sp…

This https://arxiv.org/abs/2311.09296 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_hepp…

Towards a data-driven model of hadronization using normalizing flows
We introduce a model of hadronization based on invertible neural networks that faithfully reproduces a simplified version of the Lund string model for meson hadronization. Additionally, we introduce a new training method for normalizing flows, termed MAGIC, that improves the agreement between simulated and experimental distributions of high-level (macroscopic) observables by adjusting single-emission (microscopic) dynamics. Our results constitute an important step toward realizing a machine-lea…

This https://arxiv.org/abs/2403.06708 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_mat…

Tikhonov Regularization for Stochastic Non-Smooth Convex Optimization in Hilbert Spaces
To solve non-smooth convex optimization problems with a noisy gradient input, we analyze the global behavior of subgradient-like flows under stochastic errors. The objective function is composite, being equal to the sum of two convex functions, one being differentiable and the other potentially non-smooth. We then use stochastic differential inclusions where the drift term is minus the subgradient of the objective function, and the diffusion term is either bounded or square-integrable. In this …

Fregean Flows
Eric Easthope
https://arxiv.org/abs/2403.09921 https://arxiv.org/pdf/2403.09921…

Fregean Flows
I humbly introduce a concept I call "Fregean flows," a graph theoretic representation of classical logic, to show how higher-dimensional graph characteristics might be useful to prove or perhaps at best show the provability of simple deductive statements typically represented as one-dimensional strings of characters. I apply these to a very simple proof, namely proving the equivalence of two definitions for an Abelian group G, an if-and-only-if statement, using a re-representation of statements…

This https://arxiv.org/abs/2403.16285 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_nli…

SKdV, SmKdV flows and their supersymmetric gauge-Miura transformations
The construction of Integrable Hierarchies in terms of zero curvature representation provides a systematic construction for a series of integrable non-linear evolution equations (flows) which shares a common affine Lie algebraic structure. The integrable hierarchies are then classified in terms of a decomposition of the underlying affine Lie algebra $\hat \lie $ into graded subspaces defined by a grading operator $Q$. In this paper we shall discuss explicitly the simplest case of the affine $\h…

This https://arxiv.org/abs/2210.00240 has been replaced.
link: https://scholar.google.com/scholar?q=a

Executable First-Order Queries in the Logic of Information Flows
The logic of information flows (LIF) has recently been proposed as a general framework in the field of knowledge representation. In this framework, tasks of procedural nature can still be modeled in a declarative, logic-based fashion. In this paper, we focus on the task of query processing under limited access patterns, a well-studied problem in the database literature. We show that LIF is well-suited for modeling this task. Toward this goal, we introduce a variant of LIF called "forward" LIF (…

Predicting Energy Budgets in Droplet Dynamics: A Recurrent Neural Network Approach
Diego A. de Aguiar, Hugo L. Fran\c{c}a, Cassio M. Oishi
https://arxiv.org/abs/2403.16144

Predicting Energy Budgets in Droplet Dynamics: A Recurrent Neural Network Approach
Neural networks in fluid mechanics offer an efficient approach for exploring complex flows, including multiphase and free surface flows. The recurrent neural network, particularly the Long Short-Term Memory (LSTM) model, proves attractive for learning mappings from transient inputs to dynamic outputs. This study applies LSTM to predict transient and static outputs for fluid flows under surface tension effects. Specifically, we explore two distinct droplet dynamic scenarios: droplets with divers…

This https://arxiv.org/abs/2403.05953 has been replaced.
initial toot: https://mastoxiv.page/@…

Discrete Boltzmann model with split collision for nonequilibrium reactive flows
A multi-relaxation-time discrete Boltzmann model (DBM) with split collision is proposed for both subsonic and supersonic compressible reacting flows, where chemical reactions take place among various components. The physical model is based on a unified set of discrete Boltzmann equations that describes the evolution of each chemical species with adjustable acceleration, specific heat ratio, and Prandtl number. On the righ-hand side of discrete Boltzmann equations, the collision, force, and reac…

This https://arxiv.org/abs/2004.05694 has been replaced.
link: https://scholar.google.com/scholar?q=a

Tuning upstream swimming of micro-robots by shape and cargo size
The navigation of micro-robots in complex flow environments is controlled by rheotaxis, the reorientation with respect to flow gradients. Here we demonstrate how payloads can be exploited to enhance the motion against flows. Using fully resolved hydrodynamic simulations, the mechanisms are described that allow micro-robots of different shapes to reorient upstream. We find that cargo pullers are the fastest at most flow strengths, but pushers feature a non-trivial optimum as a function of the co…

Microscopic modeling of attention-based movement behaviors
Danrui Li, Mathew Schwartz, Samuel S. Sohn, Sejong Yoon, Vladimir Pavlovic, Mubbasir Kapadia
https://arxiv.org/abs/2403.14892

Microscopic modeling of attention-based movement behaviors
For transportation hubs, leveraging pedestrian flows for commercial activities presents an effective strategy for funding maintenance and infrastructure improvements. However, this introduces new challenges, as consumer behaviors can disrupt pedestrian flow and efficiency. To optimize both retail potential and pedestrian efficiency, careful strategic planning in store layout and facility dimensions was done by expert judgement due to the complexity in pedestrian dynamics in the retail areas of …

Sampling for Model Predictive Trajectory Planning in Autonomous Driving using Normalizing Flows
Georg Rabenstein, Lars Ullrich, Knut Graichen
https://arxiv.org/abs/2404.09657

Sampling for Model Predictive Trajectory Planning in Autonomous Driving using Normalizing Flows
Alongside optimization-based planners, sampling-based approaches are often used in trajectory planning for autonomous driving due to their simplicity. Model predictive path integral control is a framework that builds upon optimization principles while incorporating stochastic sampling of input trajectories. This paper investigates several sampling approaches for trajectory generation. In this context, normalizing flows originating from the field of variational inference are considered for the g…

Monadic functors forgetful of (dis)inhibited actions
Alexandru Chirvasitu
https://arxiv.org/abs/2404.13169 https://arxiv.org/pdf/2404…

Monadic functors forgetful of (dis)inhibited actions
We prove a number of results of the following common flavor: for a category $\mathcal{C}$ of topological or uniform spaces with all manner of other properties of common interest (separation / completeness / compactness axioms), a group (or monoid) $\mathbb{G}$ equipped with various types of topological structure (topologies, uniformities) and the corresponding category $\mathcal{C}^{\mathbb{G}}$ of appropriately compatible $\mathbb{G}$-flows in $\mathcal{C}$, the forgetful functor $\mathcal{C}^…

This https://arxiv.org/abs/2401.10911 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_mat…

Variational formulation for stratified steady water wave in two-layer flows
In this paper, the variational formulation for steady periodic stratified water waves in two-layer flows is given. The critical points of a natural energy functional is proved to be the solutions of the governing equations. And the second variation of the functional is also presented.

Explicit form of simplified Grad's 13 moments distribution function-based moment gas kinetic solver with unstructured meshes for the multiscale rarefied flow
W. Liu, C. Shu, Z. J. Liu
https://arxiv.org/abs/2403.16014

Explicit form of simplified Grad's 13 moments distribution function-based moment gas kinetic solver with unstructured meshes for the multiscale rarefied flow
It is essential to efficiently solve multiscale flows covering the continuum regime to the rarefied regime. The explicit form of Grad's 13 moments distribution function-based moment gas kinetic solver (G13-MGKS) has been proposed in our previous work [Comput. Math. Appl., 137 (2023), pp. 112-125], which demonstrates the potential for efficiently simulating continuum flows accurately and presenting reasonable predictions for rarefied flows at moderate Knudsen numbers on structured meshes. To fur…

This https://arxiv.org/abs/2207.07419 has been replaced.
link: https://scholar.google.com/scholar?q=a

An exact analytical solution for the weakly magnetized flow around an axially symmetric paraboloid, with application to magnetosphere models
Rotationally symmetric bodies with longitudinal cross sections of parabolic shape are frequently used to model astrophysical objects, such as magnetospheres and other blunt objects, immersed in interplanetary or interstellar gas or plasma flows. We discuss a simple formula for the potential flow of an incompressible fluid around an elliptic paraboloid whose axis of symmetry coincides with the direction of incoming flow. Prescribing this flow, we derive an exact analytical solution to the induct…

Modeling wood product carbon flows in southern us pine plantations: implications for carbon storage
https://cbmjournal.biomedcentral.com/articles/10.1186/s13021-024-00254-4

Modeling wood product carbon flows in southern us pine plantations: implications for carbon storage - Carbon Balance and Management
Background Wood products continue to store carbon sequestered in forests after harvest and therefore play an important role in the total carbon storage associated with the forest sector. Trade-offs between carbon sequestration/storage in wood product pools and managed forest systems exist, and in order for forest sector carbon modeling to be meaningful, it must link wood product carbon with the specific forest system from which the products originate and have the ability to incorporate in situ …

This https://arxiv.org/abs/2402.02866 has been replaced.
link: https://scholar.google.com/scholar?q=a

Quantum Normalizing Flows for Anomaly Detection
A Normalizing Flow computes a bijective mapping from an arbitrary distribution to a predefined (e.g. normal) distribution. Such a flow can be used to address different tasks, e.g. anomaly detection, once such a mapping has been learned. In this work we introduce Normalizing Flows for Quantum architectures, describe how to model and optimize such a flow and evaluate our method on example datasets. Our proposed models show competitive performance for anomaly detection compared to classical method…

Deep Multi-View Channel-Wise Spatio-Temporal Network for Traffic Flow Prediction
Hao Miao, Senzhang Wang, Meiyue Zhang, Diansheng Guo, Funing Sun, Fan Yang
https://arxiv.org/abs/2404.15034

Deep Multi-View Channel-Wise Spatio-Temporal Network for Traffic Flow Prediction
Accurately forecasting traffic flows is critically important to many real applications including public safety and intelligent transportation systems. The challenges of this problem include both the dynamic mobility patterns of the people and the complex spatial-temporal correlations of the urban traffic data. Meanwhile, most existing models ignore the diverse impacts of the various traffic observations (e.g. vehicle speed and road occupancy) on the traffic flow prediction, and different traffi…

This https://arxiv.org/abs/2311.00532 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_mat…

Koopman eigenfunctions as drivers
The Koopman operator represents the dynamics induced by a dynamical system in some suitably chosen functional space. It provides a linear representation of any nonlinear system. Its eigenfunctions represent the non-mixing component $D$ of the dynamics, they factor the dynamics into linear ergodic flows on tori $\mathbb{T}^d$. The orthogonal complement (in $L^2$ space) $D^\bot$ to these eigenfunctions include the continuous spectrum of the system and this where properties like decay of correlati…

Fregean Flows
Eric Easthope
https://arxiv.org/abs/2403.09921 https://arxiv.org/pdf/2403.09921…

Fregean Flows
I humbly introduce a concept I call "Fregean flows," a graph theoretic representation of classical logic, to show how higher-dimensional graph characteristics might be useful to prove or perhaps at best show the provability of simple deductive statements typically represented as one-dimensional strings of characters. I apply these to a very simple proof, namely proving the equivalence of two definitions for an Abelian group G, an if-and-only-if statement, using a re-representation of statements…

The origin of the Slow-to-Alfv\'en Wave Cascade Power Ratio and its Implications for Particle Heating in Accretion Flows
Kaushik Satapathy, Dimitrios Psaltis, Feryal \"Ozel
https://arxiv.org/abs/2402.14089

The origin of the Slow-to-Alfvén Wave Cascade Power Ratio and its Implications for Particle Heating in Accretion Flows
The partition of turbulent heating between ions and electrons in radiatively inefficient accretion flows plays a crucial role in determining the observational appearance of accreting black holes. Modeling this partition is, however, a challenging problem because of the large scale separation between the macroscopic scales at which energy is injected by turbulence and the microscopic ones at which it is dissipated into heat. Recent studies of particle heating from collisionless damping of turbul…

This https://arxiv.org/abs/2310.03054 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_sta…

Posterior Sampling Based on Gradient Flows of the MMD with Negative Distance Kernel
We propose conditional flows of the maximum mean discrepancy (MMD) with the negative distance kernel for posterior sampling and conditional generative modeling. This MMD, which is also known as energy distance, has several advantageous properties like efficient computation via slicing and sorting. We approximate the joint distribution of the ground truth and the observations using discrete Wasserstein gradient flows and establish an error bound for the posterior distributions. Further, we prove…

Primitive chain network simulations for double peaks in shear stress under fast flows of bidisperse entangled polymers
Yuichi Masubuchi
https://arxiv.org/abs/2404.14629

Primitive chain network simulations for double peaks in shear stress under fast flows of bidisperse entangled polymers
A few experiments have reported that the time development of shear stress under fast start-up shear deformations exhibits double peaks before reaching the steady state for bimodal blends of entangled linear polymers in specific conditions. To analyze the molecular origin of this phenomenon, multi-chain slip-link simulations based on the primitive chain network model were conducted for the data of a bimodal polystyrene solution reported by Osaki et al. [J Pol Sci B Pol Phys, 38, 2043 (2000)] Owi…

This https://arxiv.org/abs/2402.08829 has been replaced.
initial toot: https://mastoxiv.page/@ar…

Percolating transition to turbulence without puffs or bands
Wall-bounded turbulent shear flows are known to be space-time intermittent at low Reynolds number. Intermittency commonly takes the form of discrete, large-scale turbulent structures, known as puffs in pipe flow or bands in planar flows, which coexist with laminar flow. These structures are sustained via robust large-scale flow that couples with turbulence. We design a numerical experiment that suppresses the large-scale spanwise velocity in plane Couette flow. The transition is then not mediat…

Integrable geodesic flows with simultaneously diagonalisable quadratic integrals
Sergey I. Agafonov, Vladimir S. Matveev
https://arxiv.org/abs/2403.14319 h…

Integrable geodesic flows with simultaneously diagonalisable quadratic integrals
We show that if $n$ functionally independent commutative quadratic in momenta integrals for the geodesic flow of a Riemannian or pseudo-Riemannian metric on an $n$-dimensional manifold are simultaneously diagonalisable at the tangent space to every point, then they come from the Stäckel construction, so the metric admits orthogonal separation of variables.

Enhancing Arterial Blood Flow Simulations through Physics-Informed Neural Networks
Shivam Bhargava, Nagaiah Chamakuri
https://arxiv.org/abs/2404.16347 http…

Enhancing Arterial Blood Flow Simulations through Physics-Informed Neural Networks
This study introduces a computational approach leveraging physics-informed neural networks (PINNs) for the efficient computation of arterial blood flows, particularly focusing on solving the incompressible Navier-Stokes equations by using the domain decomposition technique. Unlike conventional computational fluid dynamics methods, PINNs offer advantages by eliminating the need for discretized meshes and enabling the direct solution of partial differential equations (PDEs). In this paper, we pro…

This https://arxiv.org/abs/2312.02688 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_mat…

Structural stability of three dimensional transonic shock flows with an external force
We establish the existence and uniqueness of the transonic shock solution for steady isentropic Euler system with an external force in a rectangular cylinder under the three-dimensional perturbations for the incoming supersonic flow, the exit pressure and the external force. The external force has a stabilization effect on the transonic shocks in flat nozzles and the transonic shock is completely free, we do not require it passing through a fixed point. By utilizing the deformation-curl decompo…

Optimal transport maps as flows of control-affine systems
Marco Caponigro, Arianna Vicari
https://arxiv.org/abs/2404.12793 https://ar…

Optimal transport maps as flows of control-affine systems
We consider the controllability problem for the continuity equation where the dynamics is governed by a driftless control-affine system. Under suitable regularity conditions, the controllability of the system is a sufficient condition for the controllability of the continuity equation by means of time-varying feedback controls. Moreover, we show that there exist controls such that the flow of the control system is the optimal transport map, for the 2-Wasserstein distance, between two given prob…

Electron Heating in the Trans-Relativistic Perpendicular Shocks of Tilted Accretion Flows
Lorenzo Sironi, Aaron Tran
https://arxiv.org/abs/2402.13317 https…

Electron Heating in the Trans-Relativistic Perpendicular Shocks of Tilted Accretion Flows
General relativistic magnetohydrodynamic (GRMHD) simulations of black hole tilted disks -- where the angular momentum of the accretion flow at large distances is misaligned with respect to the black hole spin -- commonly display standing shocks, within a few to tens of gravitational radii from the black hole. In GRMHD simulations of geometrically thick, optically thin accretion flows, applicable to low-luminosity sources like Sgr A* and M87*, the shocks have trans-relativistic speed, moderate p…

Revisiting Crossflow-Based Stabilization in Channel Flows
Muhammad Abdullah, George Ilhwan Park
https://arxiv.org/abs/2404.14725 https://

Revisiting Crossflow-Based Stabilization in Channel Flows
Stabilization schemes in wall-bounded flows often invoke fluid transpiration through porous boundaries. While these have been extensively validated for external flows, their efficacy in channels, particularly from the standpoint of non-modal perturbations, is yet to be demonstrated. Here, we show that crossflow strengths previously considered ``ideal'' for optimizing stability in channels in fact admit strong non-modal energy amplification. We begin by supplementing existing modal calculations …

This https://arxiv.org/abs/2104.07109 has been replaced.
link: https://scholar.google.com/scholar?q=a

Surgery on Anosov flows using bi-contact geometry
Using bi-contact geometry, we define a new type of Dehn surgery on an Anosov flow with orientable weak invariant foliations. The Anosovity of the new flow is strictly connected to contact geometry and the Reeb dynamics of the defining bi-contact structure. This approach gives new insights into the properties of the flows produced by Goodman surgery and clarifies under which conditions Goodman's construction yields an Anosov flow. Our main application gives a necessary and sufficient condition t…

Locally homogeneous Axiom A flows I: projective Anosov subgroups and exponential mixing
Benjamin Delarue, Daniel Monclair, Andrew Sanders
https://arxiv.org/abs/2403.14257

Locally homogeneous Axiom A flows I: projective Anosov subgroups and exponential mixing
By constructing a non-empty domain of discontinuity in a suitable homogeneous space, we prove that every torsion-free projective Anosov subgroup is the monodromy group of a locally homogeneous contact Axiom A dynamical system with a unique basic hyperbolic set on which the flow is conjugate to the refraction flow of Sambarino. Under the assumption of irreducibility, we utilize the work of Stoyanov to establish spectral estimates for the associated complex Ruelle transfer operators, and by way o…

floZ: Evidence estimation from posterior samples with normalizing flows
Rahul Srinivasan, Marco Crisostomi, Roberto Trotta, Enrico Barausse, Matteo Breschi
https://arxiv.org/abs/2404.12294

floZ: Evidence estimation from posterior samples with normalizing flows
We propose a novel method (floZ), based on normalizing flows, for estimating the Bayesian evidence (and its numerical uncertainty) from a set of samples drawn from the unnormalized posterior distribution. We validate it on distributions whose evidence is known analytically, up to 15 parameter space dimensions, and compare with two state-of-the-art techniques for estimating the evidence: nested sampling (which computes the evidence as its main target) and a k-nearest-neighbors technique that pro…

Witnessing Flows in Arithmetic
Amirhossein Akbar Tabatabai
https://arxiv.org/abs/2404.11218 https://arxiv.org/pdf/2404.11218

Witnessing Flows in Arithmetic
One of the elegant achievements in the history of proof theory is the characterization of the provably total recursive functions of an arithmetical theory by its proof-theoretic ordinal as a way to measure the time complexity of the functions. Unfortunately, the machinery is not sufficiently fine-grained to be applicable on the weak theories on the one hand and to capture the bounded functions with bounded definitions of strong theories, on the other. In this paper, we develop such a machinery …

This https://arxiv.org/abs/2403.08544 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_…

Comparing jet-shaped point symmetry in cluster cooling flows and supernovae
I point out similarities between point-symmetric X-ray morphologies in cooling flow groups and clusters of galaxies, which are observed to be shaped by jets, and point-symmetric morphologies of eight core-collapse supernova (CCSN) remnants. I use these similarities to strengthen the jittering jet explosion mechanism (JJEM) of CCSNe, which predicts that the last pairs of jets to be launched by the newly born neutron star might shape some CCSN remnants to point-symmetric morphology. The point-sym…

This https://arxiv.org/abs/2108.09533 has been replaced.
link: https://scholar.google.com/scholar?q=a

Boundary control for optimal mixing via Stokes flows and numerical implementation
This work develops scientific computing techniques to further the exploration of using boundary control alone to optimize mixing in Stokes flows. The theoretical foundation including mathematical model and the optimality conditions for solving the optimal control has been established by Hu and Wu in a series of work. The scalar being mixed is purely advected by the flow and the control is exerted tangentially on the domain boundary through the Navier slip conditions. The control design is motiv…

This https://arxiv.org/abs/2104.07109 has been replaced.
link: https://scholar.google.com/scholar?q=a

Surgery on Anosov flows using bi-contact geometry
Using bi-contact geometry, we define a new type of Dehn surgery on an Anosov flow with orientable weak invariant foliations. The Anosovity of the new flow is strictly connected to contact geometry and the Reeb dynamics of the defining bi-contact structure. This approach gives new insights into the properties of the flows produced by Goodman surgery and clarifies under which conditions Goodman's construction yields an Anosov flow. Our main application gives a necessary and sufficient condition t…

This https://arxiv.org/abs/2312.02754 has been replaced.
initial toot: https://mastoxiv.page/@ar…

Capillary driven flows in microgravity
This work investigates the capillary rise dynamics of highly wetting liquids in a divergent U-tube in the microgravity conditions provided by 78th European Space Agency (ESA) parabolic flight. This configuration produces a capillary-driven channel flow. We use image recording in backlight illumination to characterize the interface dynamics and dynamic contact angle of HFE7200 and Di-Propylene Glycol (DPG). For the case of HF7200, we complement the interface measurements with Particle Tracking V…

Transonic shocks for steady Euler flows with an external force in an axisymmetric perturbed cylinder
Zihao Zhang
https://arxiv.org/abs/2404.14652 https://<…

Transonic shocks for steady Euler flows with an external force in an axisymmetric perturbed cylinder
We concern the structural stability of transonic shocks for the steady Euler system with an external force in an axisymmetric perturbed cylinder. For a class of external forces, we first prove the existence and uniqueness of the transonic shock solution to the one-dimensional steady Euler system with an external force, which shows that the external force has a stabilization effect on the transonic shock in the flat cylinder and the shock position is uniquely determined. We then establish the ex…

This https://arxiv.org/abs/2404.03848 has been replaced.
initial toot: https://mastoxiv.page/@arXiv_mat…

On sncc-inheritance of pointwise almost periodicity in flows
Let $H$ be a subnormal co-compact closed subgroup of a Hausdorff topological group $T$ and $X$ a compact Hausdorff space. We prove the inheritance theorem: A point of $X$ is almost periodic (a.p.) for $T\curvearrowright X$ iff it is a.p. for $H\curvearrowright X$. Moreover, if $T\curvearrowright X$ is minimal with $H\lhd T$, then $\mathscr{O}_H\colon X\rightarrow2^X$, ${x\mapsto\overline{Hx}}$ is a continuous mapping, and, $T\curvearrowright X/H$ is an a.p. nontrivial factor of $T\curvearrowrig…

Stability, convergence, and pressure-robustness of numerical schemes for incompressible flows with hybrid velocity and pressure
Lorenzo Botti, Michele Botti, Daniele Antonio Di Pietro, Francesco Carlo Massa
https://arxiv.org/abs/2404.12732

Stability, convergence, and pressure-robustness of numerical schemes for incompressible flows with hybrid velocity and pressure
In this work we study the stability, convergence, and pressure-robustness of discretization methods for incompressible flows with hybrid velocity and pressure. Specifically, focusing on the Stokes problem, we identify a set of assumptions that yield inf-sup stability as well as error estimates which distinguish the velocity- and pressure-related contributions to the error. We additionally identify the key properties under which the pressure-related contributions vanish in the estimate of the ve…

Mesoscopic Lattice Boltzmann modeling of dense gas flows in curvilinear geometries
Sergiu Busuioc
https://arxiv.org/abs/2403.15051 https://

Mesoscopic Lattice Boltzmann modeling of dense gas flows in curvilinear geometries
We derive the Enskog equation utilizing orthonormal vielbein fields, enabling the utilization of arbitrary coordinate systems to characterize spatial geometry. Additionally, we employ an adapted coordinate system in the momentum space, connected to the physical space through vielbeins. Within this framework, the momentum component perpendicular to a curved boundary can be treated as an independent one, facilitating the application of half-range Gauss-Hermite quadratures. We develop an appropria…

Mass Flows in Expanding Coronal Loops
Jeffrey W. Reep, Roger B. Scott, Sherry Chhabra, John Unverferth, Kalman J. Knizhnik
https://arxiv.org/abs/2403.12358

Mass Flows in Expanding Coronal Loops
An expansion of cross-sectional area directly impacts the mass flow along a coronal loop, and significantly alters the radiative and hydrodynamic evolution of that loop as a result. Previous studies have found that an area expansion from chromosphere to corona significantly lengthens the cooling time of the corona, and appears to suppress draining from the corona. In this work, we examine the fluid dynamics to understand how the mass flow rate, the energy balance, and the cooling and draining t…

This https://arxiv.org/abs/2309.13555 has been replaced.
initial toot: https://mastoxiv.page/@ar…

Sensitivity analysis of wall-modeled large-eddy simulation for separated turbulent flow
In this study, we conduct a parametric analysis to evaluate the sensitivities of wall-modeled large-eddy simulation (LES) with respect to subgrid-scale (SGS) models, mesh resolution, wall boundary conditions and mesh anisotropy. While such investigations have been conducted for attached/flat-plate flow configurations, systematic studies specifically targeting turbulent flows with separation are notably sparse. To bridge this gap, our study focuses on the flow over a two-dimensional Gaussian-sha…

Magnetospheric Flows in X-ray Pulsars I: Instability at super-Eddington regime of accretion
A. A. Mushtukov, A. Ingram, V. F. Suleimanov, N. DiLullo, M. Middleton, S. S. Tsygankov, M. van der Klis, S. Portegies Zwart
https://arxiv.org/abs/2402.12965

Magnetospheric Flows in X-ray Pulsars I: Instability at super-Eddington regime of accretion
Within the magnetospheric radius, the geometry of accretion flow in X-ray pulsars is shaped by a strong magnetic field of a neutron star. Starting at the magnetospheric radius, accretion flow follows field lines and reaches the stellar surface in small regions located close to the magnetic poles of a star. At low mass accretion rates, the dynamic of the flow is determined by gravitational attraction and rotation of the magnetosphere due to the centrifugal force. At the luminosity range close to…

Accelerating Aeroelastic UVLM Simulations by Inexact Newton Algorithms
Jenny Schubert, Marc C. Steinbach, Christian Hente, David M\"artins, Daniel Schuster
https://arxiv.org/abs/2403.15286

Accelerating Aeroelastic UVLM Simulations by Inexact Newton Algorithms
We consider the aeroelastic simulation of flexible mechanical structures submerged in subsonic fluid flows at low Mach numbers. The nonlinear kinematics of flexible bodies are described in the total Lagrangian formulation and discretized by finite elements. The aerodynamic loads are computed using the unsteady vortex-lattice method wherein a free wake is tracked over time. Each implicit time step in the dynamic simulation then requires solving a nonlinear equation system in the structural varia…

This https://arxiv.org/abs/2402.13328 has been replaced.
initial toot: https://mastoxiv.page/@ar…

On energy-aware hybrid models
This study proposes deterministic and stochastic energy-aware hybrid models (hybrids for short) that enable simulations of Geophysical Fluid Dynamics (GFD) models at low resolutions without compromising on quality compared with high-resolution runs. Such hybrids bridge the data-driven and physics-driven modelling paradigms by combining regional stability and classical GFD models at low resolution that cannot reproduce high-resolution reference flow features (large-scale flows and small-scale vo…

This https://arxiv.org/abs/2204.13093 has been replaced.
link: https://scholar.google.com/scholar?q=a

Symmetric doubly periodic gravity-capillary waves with small vorticity
We construct small amplitude gravity-capillary water waves with small nonzero vorticity, in three spatial dimensions, bifurcating from uniform flows. The waves are symmetric, and periodic in both horizontal coordinates. The proof is inspired by Lortz' construction of magnetohydrostatic equilibria in reflection-symmetric toroidal domains. It relies on a global representation of the vorticity as the cross product of two gradients, and on prescribing a functional relationship between the Bernoulli…

Conductive and Radiative Heat Transfer Mechanisms Inform Nusselt Number Dependence on Solid Volume Fraction for Granular Flows
Bingjia Li, Zijie Chen, Rohini Bala Chandran
https://arxiv.org/abs/2403.13974

Conductive and Radiative Heat Transfer Mechanisms Inform Nusselt Number Dependence on Solid Volume Fraction for Granular Flows
Granular flows with solid particles play an important role in energy and catalysis applications. To predict thermal performance, this study develops a comprehensive discrete particle tracking flow model fully coupled with conductive and radiative heat transfer. Leveraging LIGGGHTS, our model uniquely integrates particle-particle and particle-wall thermal radiation for grey radiative surfaces up to nearly 10 times of particle size. Models include: (a) plug flows of particles with a near-constant…

This https://arxiv.org/abs/2204.13093 has been replaced.
link: https://scholar.google.com/scholar?q=a

Symmetric doubly periodic gravity-capillary waves with small vorticity
We construct small amplitude gravity-capillary water waves with small nonzero vorticity, in three spatial dimensions, bifurcating from uniform flows. The waves are symmetric, and periodic in both horizontal coordinates. The proof is inspired by Lortz' construction of magnetohydrostatic equilibria in reflection-symmetric toroidal domains. It relies on a global representation of the vorticity as the cross product of two gradients, and on prescribing a functional relationship between the Bernoulli…

Electrohydrodynamic flows inside a neutrally buoyant leaky dielectric drop
Joel R. Karp, Bertrand Lecordier, Mostafa S. Shadloo
https://arxiv.org/abs/2402.13838

Electrohydrodynamic flows inside a neutrally buoyant leaky dielectric drop
We present for the first time an experimental investigation of electrohydrodynamic (EHD) flows within a neutrally buoyant drop with initial radius of 2.25 mm. Utilizing particle image velocimetry (PIV) and high-speed shadowgraphy, we measure the internal circulation and reported velocity profiles in the bulk and at the interface of the drop. Two leaky dielectric liquids, Silicone and Castor oils, are employed as the drop and external phase, allowing for the analysis of two shape configurations:…

An Edge-based Interface Tracking (EBIT) Method for Multiphase Flows with Phase Change
Tian Long, Jieyun Pan, St\'ephane Zaleski
https://arxiv.org/abs/2402.13677

An Edge-based Interface Tracking (EBIT) Method for Multiphase Flows with Phase Change
In this paper, the Edge-Based Interface Tracking (EBIT) method is extended to simulate multiphase flows with phase change. As a novel Front-Tracking method, the EBIT method binds interfacial markers to the Eulerian grid to achieve automatic parallelization. To include phase change effects, the energy equation for each phase is solved, with the temperature boundary condition at the interface sharply imposed. When using collocated grids, the cell-centered velocity is approximately projected. This…

An adaptive lattice Green's function method for external flows with two unbounded and one homogeneous directions
Wei Hou, Tim Colonius
https://arxiv.org/abs/2402.13370

An adaptive lattice Green's function method for external flows with two unbounded and one homogeneous directions
We solve the incompressible Navier-Stokes equations using a lattice Green's function (LGF) approach, including immersed boundaries (IB) and adaptive mesh refinement (AMR), for external flows with one homogeneous direction (e.g. infinite cylinders of arbitrary cross-section). We hybridize a Fourier collocation (pseudo-spectral) method for the homogeneous direction with a specially designed, staggered-grid finite-volume scheme on an AMR grid. The Fourier series is also truncated variably accordin…

High-order meshless global stability analysis of Taylor-Couette flows in complex domains
Akash Unnikrishnan, Vinod Narayanan, Surya Pratap Vanka
https://arxiv.org/abs/2404.11517 <…

High-order meshless global stability analysis of Taylor-Couette flows in complex domains
Recently, meshless methods have become popular in numerically solving partial differential equations and have been employed to solve equations governing fluid flows, heat transfer, and species transport. In the present study, a numerical solver is developed employing the meshless framework to efficiently compute the hydrodynamic stability of fluid flows in complex geometries. The developed method is tested on two cases of Taylor-Couette flows. The concentric case represents the parallel flow as…

This https://arxiv.org/abs/2401.09843 has been replaced.
initial toot: https://mastoxiv.page/@ar…

Efficient Computation of Large-Scale Statistical Solutions to Incompressible Fluid Flows
This work presents the development, performance analysis and subsequent optimization of a GPU-based spectral hyperviscosity solver for turbulent flows described by the three dimensional incompressible Navier-Stokes equations. The method solves for the fluid velocity fields directly in Fourier space, eliminating the need to solve a large-scale linear system of equations in order to find the pressure field. Special focus is put on the communication intensive transpose operation required by the fa…

Following marginal stability manifolds in quasilinear dynamical reductions of multiscale flows in two space dimensions
Alessia Ferraro, Gregory P. Chini, Tobias M. Schneider
https://arxiv.org/abs/2403.13971

Following marginal stability manifolds in quasilinear dynamical reductions of multiscale flows in two space dimensions
A two-dimensional extension of a recently developed formalism for slow-fast quasilinear (QL) systems subject to fast instabilities is derived. Prior work has demonstrated that the emergent dynamics of these systems is characterized by a slow evolution of mean fields coupled to marginally stable, fast fluctuation fields. By exploiting this emergent behavior, an efficient fast-eigenvalue/slow-initial-value solution algorithm can be developed in which the amplitude of the fast fluctuations is slav…

This https://arxiv.org/abs/2402.07105 has been replaced.
initial toot: https://mastoxiv.page/@ar…

Unified Framework for Laser-induced Transient Bubble Dynamics within Microchannels
Oscillatory flow in confined spaces is central to understanding physiological flows and rational design of synthetic periodic-actuation based micromachines. Using theory and experiments on oscillating flows generated through a laser-induced cavitation bubble, we associate the dynamic bubble size (fluid velocity) and bubble lifetime to the laser energy supplied - a control parameter in experiments. Employing different channel cross-section shapes, sizes and lengths, we demonstrate the characteri…

Accuracy Assessment of Discontinuous Galerkin Spectral Element Method in Simulating Supersonic Free Jets
Diego F. Abreu, Jo\~ao Luiz F. Azevedo, Carlos Junqueira-Junior
https://arxiv.org/abs/2403.14272

Accuracy Assessment of Discontinuous Galerkin Spectral Element Method in Simulating Supersonic Free Jets
The study performs large-eddy simulations of supersonic free jet flows using the Discontinuous Galerkin Spectral Element Method (DGSEM). The main objective of the present work is to assess the resolution requirements for adequate simulation of such flows with the DGSEM approach. The study looked at the influence of the mesh and the spatial discretization accuracy on the simulation results. The present analysis involves four simulations, incorporating three different numerical meshes and two dif…