On the Indeterminateness of the Boundary Conditions for the Mixing of Two Parallel Streams

Abstract

Results obtained from a study of the indeterminateness of the boundary conditions for laminar “free” mixing of two parallel streams under constant pressure are presented in this paper. A method is given for the determination of the interface velocity, the location of the interface in the mixing region, and the transverse force acting on the dividing wall as a consequence of the mixing. Based on available numerical data, calculations have been made for two free-stream velocity ratios, 0.5 and 0. It is shown that values of interface velocity obtained here differ appreciably from those obtained using other proposed boundary conditions (the third condition). In addition, for a free-stream velocity ratio of 0.5 the interface deflects toward the higher velocity stream, while for a zero free-stream velocity ratio it deflects toward the zero (lower) velocity stream.