Numerical Simulation of Flows inside the Oral Cavity of Blackfish

Abstract

The INS 3 D-code, a finite-difference code originally developed to simulate incompressible flow past a single grid object, is modified to simulate flow into, through and around the oral cavity of the blackfish (Orthodon microlepidotus). The geometry of the mouth of the blackfish is represented by a cone with three slanted slits on each of two sides. These slits represent the gaps between the gill arches where fluid entering the mouth escapes. The computational domain is represented by its own grid placed inside O-type cylindrical grids representing the front and exterior of the mouth. Our simulations show that gill-arch structures direct the flow of water to the roof of the oral cavity, where feed particles are retained. The inclination of the gill arch and the effects of the Reynolds number determine the amount of flow directed upwards and thus the path of the food particles and the resistance on the fish due to the fluid.