STOKES-FLOW THROUGH A ROW OF CYLINDERS BETWEEN PARALLEL WALLS - MODELFOR THE GLOMERULAR SLIT DIAPHRAGM

As a model for flow through the slit diaphragms which connect the epit helial foot processes of renal glomerular capillaries, finite element solutions of Stokes equations were obtained for flow perpendicular to a row of cylinders confined between parallel walls. A dimensionless '' additional resistance'' (f), defined as the increment in resistance ab ove the Poiseuille flow value, was computed for L/W less-than-or-equal -to 4 and 0.1 less-than-or-equal-to R/L less-than-or-equal-to 0.9, whe re L is half the distance between cylinder centers, W is half the dist ance between walls and R is the cylinder radius. Two factors contribut ed to f: the drag on the cylinders, and the incremental shear stresses on the walls of the channel. Of these two factors, the drag on the cy linders tended to be dominant. A more complex representation of the sl it diaphragm, suggested in the literature, was also considered. The pr edicted hydraulic permeability of the slit diaphragm was compared with experimental values of the overall hydraulic permeability of the glom erular capillary wall.