A simulation method for muscle-driven swimming and its applications

Abstract

A novel muscle-driven method (MDM) with its corresponding Compute Unified Device Architecture parallel computational code is newly developed to mimic shortening and lengthening of muscles, in a fish-like swimming body, which causes the body flapping in the transversal direction and create a thrust force to propel the body to cruise in the longitudinal direction. In this method, the fish body is discretized as mass points connected by elastic springs and muscle deformation is critically realized by using a constraint algorithm, called RATTLE, to control relative deformation distances between neighboring mass points of the muscles, while turbulent fluids are treated by a multi-relaxation time lattice Boltzmann method with a large eddy simulation. A validation for the MDM is extensively conducted by comparing our simulation results with the existing experimental and theoretical results. Subsequently, the frequency, amplitude, and wavelength of lengthening of muscles and the stiffness and mass density of the body are systematically varied at different levels and their effects on flapping and cruising motion and flow structures are studied at different Reynolds numbers.