Meeting Abstract

80.1  Friday, Jan. 7  A computational modelling perspective on buccal expansion dynamics and water flow patterns in suction feeding fish VAN WASSENBERGH, S*; AERTS, P; Univ. Antwerpen; Univ. Antwerpen sam.vanwassenbergh@ua.ac.be

By performing a sudden expansion of the mouth cavity while approaching a prey, suction feeders generate a flow of water that draws the prey into the mouth. This process involves extremely unsteady flow, externally as well as internally of the expanding mouth cavity. Especially for flow patterns inside the mouth cavity and related dynamics (e.g. the forces, muscle power requirements and energetics for expanding the buccopharyngeal cavity) our current knowledge is largely based on modelling studies. An overview is given of our recent insights based on models of fish using the computational fluid dynamics (CFD) method. CFD shows a gradually developing boundary layer, which causes the highest velocity stream to be central in the expanding cavity, with peak velocities slightly posterior of the mouth aperture. Consequently, although related to size, the effects of viscous forces in the flow can generally not be neglected. The displacement of freely-suspended, non-reacting prey items by suction is entirely independent of the shape of the prey. Finally, the (hydro)dynamical consequences of opening of the opercular and branchiostegal valves are explored, since this distinguishes the unidirectional nature of suction feeding in fish from bidirectional suction feeding as observed in amphibians or turtles.