The application of multi-body dynamics theory on fish locomotion

Propulsion and manoeuvring ability are parts of the most common and complicated mechanisms in nature, such as fish swimming in the water and birds flying in the sky. In order to get a deep understanding of these problems, a comprehensive and completed replication of fish movements is carried out in this project. By combining with multi-body dynamic theory, the fish can be composed by a few serial elements as main body and two symmetric elements as pectoral fins, one for each side. All the elements are connected by hinges. Commercial software FLUENT is used to solve flow field. For propulsion part, swimming tests are performed under two different conditions by varying the frequency and amplitude of the angular motion at the hinges. In terms of manoeuvring ability, 3D cases will be carried out. The motion of pectoral fins is prescribed in order to simulate the up and down motion of fish in the water. Modelling results will be presented with detailed analysis on the hydrodynamic forces, vortex structure near fish body/fins and the related fish propulsion and manoeuvre performance.