An inflation–deflation propulsion system inspired by the jet propulsion mechanism of squids and other cephalopods is proposed. The two-dimensional squid-like swimmer has a flexible mantle body with a pressure chamber and a nozzle that serves as the inlet and outlet of water. The fluid–structure interaction simulation results indicate that larger mean thrust production and higher efficiency can be achieved in high Reynolds number scenarios compared with the cases in laminar flow. The improved performance at high Reynolds number is attributed to stronger jet-induced vortices and highly suppressed external body vortices, which are associated with drag force. Optimal efficiency is reached when the jet vortices start to dominate the surrounding flow. The mechanism of symmetry-breaking instability under the turbulent flow condition is found to be different from that previously reported in laminar flow. Specifically, this instability in turbulent flow stems from irregular internal body vortices, which cause symmetry breaking in the wake. A higher Reynolds number or smaller nozzle size would accelerate the formation of this symmetry-breaking instability.

中文翻译：

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以雷诺数高的鱿鱼为灵感的游泳者的脉冲喷射推进

提出了一种受鱿鱼和其他头足类动物的喷气推进机制启发的充气-放气推进系统。二维鱿鱼状游泳者具有柔软的外套，带有压力室和用作水的入口和出口的喷嘴。流体-结构相互作用模拟结果表明，与层流情况相比，在高雷诺数情况下可以实现更大的平均推力产生和更高的效率。高雷诺数下性能的改善归因于更强的射流诱发的涡旋和高度抑制的外部涡旋，它们与阻力相关。当射流涡流开始占主导地位时，达到了最佳效率。发现在湍流条件下对称破坏不稳定性的机理不同于先前在层流中报道的机理。具体而言，湍流中的这种不稳定性源于不规则的内部漩涡，这会导致尾流对称性破坏。更高的雷诺数或较小的喷嘴尺寸将加速这种破坏对称的不稳定性的形成。