On the transport of epididymal fluid induced by the metachronal wave of cilia

In this study, we investigate the propulsion mechanism of cilia involved in the flow of epididymal material through the ductus efferentes. Assuming that the rheological characteristics of the material behave as a micropolar fluid, we formulate a mathematical model for the axially symmetric flow through a cylindrical tube whose inner surface is covered with cilia. Long wavelength and the creeping flow approximations are adopted to linearize the mathematical equations. Exact solutions for the axial velocity, pressure gradient, and stream function are obtained. Special attention is paid to examine the pumping and the trapping phenomena due to the ciliary metachronism inside the tube. A comparative analysis of theoretical and experimental results indicates that a micropolar fluid describes the behavior of epididymal material more realistically than a Newtonian fluid.