Published online by Cambridge University Press: 26 March 2024
The hydrodynamics of a self-propelling swimmer undergoing intermittent S-start swimming are investigated extensively with varying duty cycle $DC$, swimming period
$T$, and tailbeat amplitude
$A$. We find that the steady time-averaged swimming speed
$\bar {U}_x$ increases directly with
$A$, but varies inversely with
$DC$ and
$T$, where there is a maximal improvement of
$541.29\,\%$ over continuous cruising swimming. Our results reveal two scaling laws, in the form of input versus output relations, that relate the swimmer's kinematics to its hydrodynamic performance: swimming speed and efficiency. A smaller
$DC$ causes increased fluctuations in the swimmer's velocity generation. A larger
$A$, on the other hand, allows the swimmer to reach steady swimming more quickly. Although we set out to determine scaling laws for intermittent S-start swimming, these scaling laws extend naturally to burst-and-coast and continuous modes of swimming. Additionally, we have identified, categorized and linked the wake structures produced by intermittent S-start swimmers with their velocity generation.