Meeting Abstract
P3.114 Sunday, Jan. 6 The scaling of suction feeding mechanics as predicted by inviscid flow models OLAIVAR, A F*; BROWN, M D; BERG, O; MULLER, U K; California State University, Fresno; California State University, Fresno; California State University, Fresno; California State University, Fresno umuller@csufresno.edu
Suction feeding is a common method of prey capture in aquatic organisms: an imposed pressure gradient causes water (and prey) to flow from the surroundings to an area of negative pressure within the mouth. Suction-feeding organisms described in the literature range in size from ~1 m (baleen whale Janjucetus hunderi) to ~1 mm (bladderwort Utricularia), with corresponding Reynolds numbers in the range 2000-200. Nevertheless, the peak fluid speeds reported for feeding strikes are strikingly similar: 1-2 m/s at the mouth aperture. In the context of our investigation of bladderwort, we consider the mechanical basis of this observation. In all cases that have been documented in sufficient detail, the suction-feeding flows are found to be effectively inviscid (inertial considerations dominating viscosity) and incompressible. The corresponding Eulerian equations of motion predict that the limiting flow speed will depend on the imposed pressure drop only, not on aperture dimensions. This dependence is furthermore sublinear (pressure1/2), so the range of biologically achievable peak pressures translates to a narrow range of peak speeds, as observed. In cases of unsteady flow, the Eulerian analysis makes additional predictions: fluid acceleration will depend only on pressure drop and channel length, and the time required to reach steady state will be vary inversely with pressure drop. We test these predictions using published data and our own studies of bladderwort.
