Computational framework for efficient high-fidelity optimization of bio-inspired propulsion and its application to accelerating swimmers
Computational framework for efficient high-fidelity optimization of bio-inspired propulsion and its application to accelerating swimmers
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DOI：
10.1016/j.jcp.2023.112038
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发表时间：
2023-03
期刊：
影响因子：
--
通讯作者：
Ahmed Abouhussein;Y. Peet
中科院分区：
文献类型：
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作者：
Ahmed Abouhussein;Y. Peet
开发了一种新的计算框架，用于自推进波动游泳期间运动学步态的高保真度优化。计算框架利用移动贴体网格上的谱元方法来模拟自推进游泳，以及基于代理的优化（SBO）程序。提出了一种新的体积守恒方法，用于重建游泳者波动运动期间的几何形状，以确保不可压缩流动框架中流固耦合求解器的数值稳定性。这项工作采用并进一步开发了一种利用克里金响应面法的基于代理的优化算法，以在鱼体运动存在生理约束的情况下管理优化过程。建立优化结果的网格收敛性，并评估多项式细化对优化过程结果的影响。多项式阶数的增加不会改变运动的最佳步态或模式之间的相对效率排名，但会导致所有模式的预测效率稍低。最佳解决方案的特点是运动步态能够产生与高推进效率相关的反向卡门涡街。发现次优模式的效率随着游泳者的尾部幅度和有效扑动长度的增加而增加，并且提出了一种新的缩放定律来捕捉这些趋势。最后，SBO 算法收敛到优化门，其函数评估次数明显少于通常观察到的进化算法。这表明 SBO 框架非常适合流体和结构问题的高保真度优化。
A new computational framework for high-fidelity optimization of kinematic gaits during self-propelled undulatory swimming is developed. A computational framework utilizes a spectral-element method on moving body-fitted grids for a simulation of self-propelled swimming, and a surrogate-based optimization (SBO) procedure. A new volume-conservation method for reconstruction of a swimmer's geometry during the undulatory motion is proposed to ensure numerical stability of the fluid-structure interaction solver in an incompressible flow framework. A surrogate-based optimization algorithm that utilizes a Kriging response surface method is adopted and further developed in this work to manage the optimization process in the presence of physiological constraints on the fish body motion. A grid convergence of the optimization results is established, and the influence of the polynomial refinement on the results of optimization procedure is assessed. The increase in polynomial order does not change the optimum gaits of locomotion or relative efficiency rankings between the modes, but it results in slightly lower predicted efficiency for all the modes. The optimum solution is characterized by a kinematic gait that generates the reverse Karman vortex street associated with high propulsive efficiency. Efficiency of sub-optimum modes is found to increase with both the tail amplitude and the effective flapping length of the swimmer, and a new scaling law is proposed to capture these trends. Lastly, the SBO algorithm converged to an optimized gate with significantly less function evaluations than typically observed for evolutionary algorithms. This suggests that the SBO framework is a well suited alternative for high-fidelity optimization of fluid and structure problems.