Dependence of capillary flow resistance upon the width of the marginal layer and the viscosity of the axial core.

Capillary blood flow may be considered as the flow of two compartments a.) the low viscous cell free marginal layer, surrounding b.) the higher viscous axial core. If the flow of both compartments is calculated separately according to Poiseuille, the addition of the two calculations allows to adapt Poiseuille's law to the non-Newtonian blood flow in small capillaries. The modified law correlates theoretical and experimental data with R2 = 0.99. (H = 0.3 - 0.7, tau W = 0.1 - 1.2 Pa, blood viscosity 5 to 20 mPa X s, capillary I.D. 0.3 mm). The width of the marginal was calculated by relating the shear dependent change in electrical resistance in blood perfused capillaries to the development of a cell free marginal layer. The viscosity of the core was determined with a bended glass fibre (phi = 10 microns).