Speaker
Description
A body immersed in a fluid (swimmer) can move by deformation or by shifting its centre of mass. We assume that both actions are periodic and that the force acting on the body is zero. For simplicity, we assume that the problem has cylindrical symmetry.
Considering a linear fluid-solid model, the body will exhibit oscillatory motion, but with a zero mean velocity. This changes when nonlinearities by the Navier-Stokes equations are introduced.
We aim to identify configurations that lead to large average velocities. The numerical approximation of this problem is challenging due to two reasons: First, the average velocity is always orders of magnitude smaller than the amplitude of the oscillation. Second, the transition of the dynamical problem to the periodic limit, where the average can be observed with certainty, can take many iterations. The convergence is slow because it depends only on the viscous damping, and usually convergence is not monotonic.
We present the numerical modeling of this problem using an ALE formulation of the fluid-solid interaction problem. We also present ideas and realizations to improve the convergence towards the periodic limit cycles.
