Mathematical analysis of coaxial disk cellular shear loading devices

Coaxial disk devices are widely used at low Reynolds numbers to simulate ce llular shear loading. Here, we develop a mathematical theory for analyzing fluid behavior in these instruments. It improves upon classical results by accounting for both unsteady dynamics and wall drag effects. All previous m odels are shown to be special cases of the present one. Most devices utiliz e a low aspect ratio, for which we find wall effects to be limited to small regions near the periphery. In these cases, classical theory yields accept able precision over most of the domain. Investigators commonly simulate pul satile effects using low-frequency sinusoidal forcing. Results indicate tha t fluid motion remains essentially harmonic, permitting the exact solution to be approximated by a simple separable expression. This approximation sho uld be useful in analyzing specific configurations. A wavelike flow mode co njectured to exist at high Strouhal numbers is also discussed. (C) 2001 Ame rican Institute of Physics.