A three-layer semi-empirical model for flow of blood and other particulate suspensions through narrow tubes.

A three-layer mathematical model has been developed and tested for calculating the velocity profile and wall layer thickness for the flow of blood and other particulate suspensions in narrow tubes, from measurements of apparent viscosity and mean concentration in tube. The model consists of a thin cell-free layer, accounting for wall exclusion effect, a cell-depleted one due to radial cell migration and a central core with uniform cell concentration. It is shown that this model contains several previously published models as particular cases and that it gives more realistic predictions of velocity profiles from the same data than less refined models. With proper adjustment of its parameters it is applicable satisfactorily to a wide variety of suspensions. The model results confirm the importance of cell deformability on blood rheological properties in capillaries less than 100 mu.