Three-dimensional finite element hydrodynamical modeling of straight and spiral cochlea

A stabilized finite element scheme for the 3D cochlear fluid-structure interaction (FSI) problem is proposed. The FSI involves the interaction between the cochlear basilar membrane (BM) and its surrounding fluid. The BM is assumed to be an orthotropic membrane, governed by Mindlin plate theory. Since the cochlear fluid is an incompressible viscous fluid, mixed displacement/pressure element with Galerkin/Least-Square(GLS) stabilization is adopted. The fluid domain and solid domain are coupled between the interface with continuous displacement, and the fluid traction applies normal pressure load on the BM, causing the BM traveling wave. Based on this scheme, numerical simulations for the traveling wave are conducted on straight and spiral 3D cochlear models. The spiral effects are discussed by comparison between straight and spiral models. There is no significant difference for the traveling motion (both the BM magnitude and phase) at the middle-line of BM. A radial pressure tilt is found in the spiral model. The fluid pressure at inner areas is relatively lower than that at outer areas. This pressure tilt becomes especially obvious near the CF (characteristic frequency) location. Nevertheless, no obvious variation of the BM displacement in the radial direction is found in the current model.