Simulation of fish escape and swimming toward a predefined goal

Abstract

We present an immersed boundary method for numerical simulation of a swimming

fish. The vorticity transport equation is solved on a Cartesian grid using compact finite dif- ferences. A Lagrangian structured grid defines the fish body and is moving in the surrounding incompressible flow due to the exerted hydrodynamic forces and the torque. An efficient law determining the curvature of a swimming fish is presented which is based on the geometrically exact theory of nonlinear beams and quaternions. Validation of the solver shows the efficiency and expected accuracy of the algorithm for swimming fish simulations. The structure of the wake of a swimming fish is studied, and some common features with the wake of a flapping plate

are demonstrated.