Numerical Investigation on Propulsion by Undulating Plate

Abstract

Unsteady viscous flow field around an undulating advancing plate in low Reynolds number range is numerically studied. The main objective is to study the abilities of an undulating plate to produce thrust and achieve higher propulsive efficiency in low Reynolds number range. The Reynolds number based on the oncoming velocity and the plate length is 1000. The flow around an undulating plate is simulated by solving the full 3 D unsteady Navier-Stokes equation in a primitive value formulation. The numerical scheme is based on the MAC method where the Navier-Stokes equation is solved by the time marching method on a body fitted coordinate system.The simulation shows that pressure is acting as thrusting force while frictional force is acting as resistance during the undulating motion. Strouhal number is the most important governing parameter for the propulsive efficiency. The propulsive efficiency is enhanced with the increase of the Reynolds number. The advancing thrust mainly comes from the aft part of the plate and the modification of the plate shape can improve the propulsive efficiency. The present study is expected to be applied for the development of a propulsor for micro-hydro-machine.