Blood flow: velocity profile continuity near a wall

Abstract

The velocity profile of flowing blood has been variously suggested as (i) smooth and continuous (the classical view) and (ii) discontinuous in a step-wise fashion (the sigma view). Interferometric observations of red blood cell velocity variations, in a near-wall vicinity at small velocities, were compared to limiting values predicted from continuous velocity profile considerations coupled with a plasma no-slip boundary condition. Some 92.5 percent of the observations are in accord with the assumed continuity. Thus scant support is given the sigma model concept. An appendix provides practical notes on blood flow interferometry.