ARTERIAL BIFURCATION FLOWS - EFFECTS OF FLOW-RATE AND AREA RATIO

Velocity profiles and surface shear rates for 3 model symmetrical bifurcations made of glass from dimensions based on the arterial system were investigated. The models studied had area ratios of 0.75, 1.02 and 1.29 with a common included angle of 75.degree.. Area ratio and parent tube flow rate were the 2 independent variables evaluated. Measurements were made with a tracer particle technique using cinephotography. Velocity profiles had their highest values on the inside and lowest values on the outside of the branch. Flow symmetry existed in the plane perpendicular to the plane of the bifurcation. Surface shear rates remained well above the daughter-tube developed values between 2 and 6 diameters downstream from the carina. Shear rates below the daughter-tube developed value were found on the outside wall between the carina and 2 daughter-tube diameters downstream. Vortex-like flow was absent in this region for the 0.75 area ratio branch and was found above 900 Reynolds no. in the 1.29 area ratio branch. The disturbed flow described by others in this region may not contain vortex-like streamlines for the physiologically important 0.75 area ratio.