Flow Physics of Routine Turns of Koi Carp (Cyprinus Carpio Koi)

摘要

References(26) Cited-By(1) This paper investigates the flow physics of Koi carp's routine turns with a novel CFD method solving the body-fluid interaction problem, which consists of deforming body dynamics and unsteady fluid dynamics. Firstly, the dynamical equations of the deforming body are presented. Secondly, the coupled equations of body dynamics and fluid dynamics are solved together. The numerical simulation is based on the kinematics data from a video tracking measurement system and the predicted body kinematics and flow visualization are well agreed with the experimental results. Single-beat turn and cruising turn are the basic two turning modes of Koi carp, and the former is the mostly observed. Through comparative studies of the turning maneuverability performance and energetics of these two kinds of turns, their common flow control mechanisms and different features are discovered, such as (1) agility (defined as turning rate) is correlated positively with maneuverability (defined as the reciprocal of the turning radius), (2) the total power appears good linear relation with the turning rate, and (3) single-beat turns are more efficient than cruising turns.