Scaling laws for the intermittent swimming performance of a flexible plate at low Reynolds number

Abstract

Many species of fish and birds travel in intermittent style, yet the combined influence of intermittency and other body kinematics on the hydrodynamics of a self-propelled swimmer is not fully understood. By formulating a reduced-order dynamical model for intermittent swimming, we uncover scaling laws that link the propulsive performance (cursing Reynolds number Re_c, thrust T̄, input power P̄ and cost of transport COT to body kinematics (duty cycle DC, flapping Reynolds number Re_f). By comparing the derived scaling laws with the data from several previous studies and our numerical simulation, we demonstrate the validity of the theory. In addition, we found that Re_c, T̄, P̄ and COT all increase with the increase of DC, Re_f. The model also reveals that the intermittent swimming may not be inherently more energy efficient than continuous swimming, depending on the ratio of drag coefficients between active bursting and coasting.