COMPARISON OF CONVERGING AND DIVERGING RADIAL FLOW FOR MEASURING CELL-ADHESION

Radial flow between parallel surfaces produces a spatially dependent w all shear stress that permits investigation of cell adhesion for a ran ge of shear simultaneously. The maximum for this range is limited by a ccurate prediction of fluid mechanics at small radial positions. Numer ical and analytical models for predicting fluid mechanics demonstrate that corner and inertial effects at small radial positions are not onl y significant but differ with the direction of flow (i.e., converging us. diverging). For diverging flow fr om an axially oriented inlet, th e recirculation zone downstream of the corner disturbs streamlines at small radial positions. With converging pow this recirculation zone is confined to the axially oriented outlet. Also, inertia contributes po sitively for converging pow, enhancing the magnitude of shear stress, but negatively for diverging flow. Experiments with cells support the validity of this analysis: the strength of cell adhesion does not vary with direction or magnitude of flow.