Abstract

This paper investigates the formation mechanism of the propulsive force of a flapping airfoil, which performs harmonic angular oscillations in a continuous medium flow, in the light of the recently proved general theorem on the added mass of bodies in a viscous incompressible fluid. The flow is described by the Navier–Stokes equations. The calculations were performed by the mesh-free numerical method of viscous vortex domains. This work explains the formation mechanism of a reverse vortex street in the wake behind the flapping airfoil in the forward thrust mode. The dominant contribution of the added mass force to the value of the propulsive force is detected. The obtained results reveal to some extent the hydrodynamic action mechanism of the tail fin of underwater animals.

中文翻译：

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附加质量力对粘性流体中拍打翼型推进力形成的贡献

摘要

根据最近证明的关于粘性不可压缩流体的附加质量的一般定理，本文研究了拍打翼型推进力的形成机理，该翼型在连续的介质流中执行谐波角振荡。流量由Navier–Stokes方程描述。通过粘性涡旋域的无网格数值方法进行计算。这项工作解释了在前推力模式下拍打翼型后面的尾流中反向涡街的形成机理。检测到增加的质量力对推进力值的主要贡献。所得结果在一定程度上揭示了水下动物尾鳍的水动力作用机理。