The studies on the flow characteristics in the bifurcation, where a single cylindricalbranch leaves the parent trunk have been recently undertaken in Ref 1 and 2. In. Ref 1the manner in which the flow divides at an arterial junction was experimentallyestablished in terms of the significant dimensionless parameters: the entranceReynolds number Re, the ratio of the side branch diameter to the main branch diameter B,and the dimensionless angle of branching.

The point which should be brought up now is the relative resistances of the pipingsystems associated with each of the branches. It is obvious that the mass flow divisionwill depend on these resistances. In the employed apparatus no provision was made tocontrol the outflow resistances of the branches. so that the mass flow rates are determinedby the local branch sizes and geometric arrangement. However. the purpose of the presentpaper is to report the existence of the basic phenomenon. Its derivatives can be determinedif desired.