Micro and Macro Fluidic Effects in Cochlear Mechanics.

Cochlear Mechanics;Wave Propagation;Fluid-structure Interaction;Fluid Viscosity;Multiscale Modleling;Mechanical Engineering;Engineering;Mechanical Engineering

Li, YizengHulbert, Gregory M. ;

University of Michigan

关键词: Cochlear Mechanics;    Wave Propagation;    Fluid-structure Interaction;    Fluid Viscosity;    Multiscale Modleling;    Mechanical Engineering;    Engineering;    Mechanical Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/98059/yizengli_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

The cochlea is a fluid-filled organ with multiple structures. The scales of the structures in the cochlea range from millimeter (macro) to sub-micrometer (micro). In this work, both the micro and macro fluidic effects in cochlear mechanics are studied to understand the working mechanism of the cochlea. Topics include wave generation and propagation, fluid viscosity, complex boundary conditions for fluid-structure interactions, power flow, and inverse problems. In addition, a method is developed to bridge the gap for the modeling effort among different scales. This method is applicable to other fluid-structure coupling problems with multiple scales.The entire work is based on a physiologically-based finite element cochlear model that couples mechanical, electric, and acoustic fields. On the macro scale, the direction of wave propagation is studied under various stimulation methods, including acoustic, bone conduction, internal force, and internal pressure sources excitations. In a passive cochlea, the reciprocity relation holds. The effect of structural (active component) perturbations on the wave propagation is also analyzed. Multiple sources are identified to the contribution of the extended ringings of the basilar membrane under an impulse response. The power dissipation and amplification are analyzed in the cochlear channels as well.On the micro scale, the viscous flow in the sub-tectorial membrane region is modeled. The flow is coupled to the motion of surrounding micro structures. The micro fluid is also coupled to the macro fluid. The model combines both analytical solutions for the micro fluid-structure interaction and numerical solutions for the intermediate and macro scale fluid behaviors. The interactive usage of analytic and numerical solutions makes the multiscale model computationally efficient and physically interpretable. This model provides a tool to determine the spatial dependence of flow modality in the sub-tectorial membrane region; determine the relative importance of motility (either outer hair cell somatic or hair bundle motility) on inner hair cell hair bundle stimulation; and analyze the role of the Hessen;;s stripe and the noise to signal ratio in the hearing.