Numerical study on the dynamics of organism motion under background flow

Abstract

We propose a two-dimensional numerical model to investigate the dynamic behaviour of an organism swimming in a background flow in a channel. In this work, the organism is modeled as a neutrally buoyant one-dimensional elastic filament based on an immersed boundary finite volume method. Further, the organism is modeled using discrete number of immersed boundary points and the Navier-Stokes equations governing the flow are solved on a staggered Cartesian grid system. A driving function is applied which results in a wave travelling along the length of the organism from left to right. It is found that under no background flow, the organism swim in the forward direction (right to left) when the wave travel over the organism is in the opposite direction. It is observed that, under a uniform background flow, a non-motile organism is simply dragged by the flow whereas a motile organism swims backward along the direction of flow. Further, it is seen that a propulsion enhancement is found in the case of organism swimming along the flow direction when the wave travel is in the opposite direction as that of the flow. � 2017 Association for Computing Machinery.