Velocity distribution and other characteristics of steady and pulsatile blood flow in fine glass tubes 1

The flow of ACD-treated human blood through hollow precision drawn glass fibers 40 to 70μ in lumen has been observed with high speed microcinematography, both under steady and pulsating conditions (the latter at values of the pulsatile Reynolds number a less than 0.36).

Analysis of the data included velocity distributions of the erythrocytes (for pulsating flow at several points in a pressure cycle), peripheral layer characteristics, pressure losses and erythrocyte rotation rates.

In pulsating flow, the velocity distributions were in phase with the pressure gradient, and the peripheral layer dimensions were not noticeably different from those for steady flow, providing a microscopic confirmation of the negligible effect, in smaller vessels, of inertial effects due to the pulsating nature of the flow. The velocity distributions for both steady and pulsating conditions fell generally between those described by models which assume the erythrocytes to be either uniformly distributed in the cross section, or concentrated in a central region of uniform radius.