@arXiv_physicsfludyn_bot@mastoxiv.page2026-05-19 08:09:26
Elastic wave propagation governs impulse enhancement in pulsed jets through flexible nozzles
Paras Singh, Daehyun Choi, Saad Bhamla, Chandan Bose
https://arxiv.org/abs/2605.17319 https://arxiv.org/pdf/2605.17319 https://arxiv.org/html/2605.17319
arXiv:2605.17319v1 Announce Type: new
Abstract: Inspired by cephalopod jet propulsion through compliant funnels, this study investigates elastic wave propagation and energy exchange in passively deforming cylindrical nozzles through three-dimensional, two-way fluid-structure interaction simulations. Flexible nozzles with varying stiffness ($Eh = 75 - 500~\mathrm{N\,m^{-1}}$, where $E$ and $h$ are Young's modulus and nozzle thickness, respectively) are subjected to a pulsatile jet inflow at $Re \sim 4000$. Increasing nozzle flexibility reduces the deformation-wave speed in accordance with Moens-Korteweg scaling, thereby prolonging the nozzle expansion phase. This delayed expansion enhances jet entrainment and elastic energy storage while suppressing early shear-layer roll-up and vortex formation. During contraction, the stored elastic energy is released, thereby enhancing jet acceleration and vortex formation. For the most flexible nozzle, the primary vortex-ring circulation increases by 52.13%, the vortex convection distance by 9.00%, and the peak outlet kinetic energy flux by a factor of 4.62 compared with a rigid nozzle. These effects collectively yield a 61.92% increase in total hydrodynamic impulse. These findings identify passive wave-speed tuning via nozzle compliance as a mechanism to enhance pulsed-jet thrust for bio-inspired underwater propulsion.
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