The influence of radial distribution and marginal plasma layer on the flow of red cell suspensions 1

Abstract

The flow of red cell suspensions ranging in hematocrit from 0 to 45 were studied in tube diameters ranging from 72 μ to 2000 μ Suspension viscometry was determined by cone and plate viscometers between shear rates of 1 sec⁻¹ and 1500 sec⁻¹. The characteristics of an idealized marginal layer were calculated from pressure-flow rate measurements.

The distribution of cells determined by Palmer [Am. J. Physiol. 209, 1115, 1965], in a 35 μ rectangular tube, was adapted to the calculation of flow rates over a wide range of conditions. Remarkably close agreement was observed with experimental data for hematocrits below 40 per cent. For hematocrits above 40 in tube diameters greater than 155 μ, radial cell distribution does not occur to any great extent and a laminar flow equation, which includes the effect of yield stress first suggested by Scott Blair and Reiner [Nature, Lond. 184, 354, 1959], describes flow up to a Reynolds number of 800.

Poiseuille’s equation applies when the dimensionless group (yield stress)/(velocity)² density is less than 5 × 10⁻⁴ and tube diameters are greater than 155 μ and hematocrits are greater than 40.