Mechanism of Periodical Fluid Oscillation Induced by Separating High Shear Rate Flow in Side Branch of Right-Angle Branch

Abstract

In the previous study, it has been clarified in the right-angle branch that the periodical oscillation flow is induced in the side branch and the Strouhal number based on the variables in the side branch is independent of the Reynolds number, the flow division ratio, and the radius of the side branch. This periodical oscillation appears along the boundary between two pairs of vortices with the opposite rotation at the cross section of the side branch across the separation flow. In the present study, another source of the periodical oscillation is experimentally clarified that the high shear rate flow is induced along the separation shearing layer between the separation flow of low velocity and the main flow with high velocity along the distal wall in the side branch since the high shear rate along this separation shearing layer is several times as large as that in the upstream trunk or in the downstream region of the side branch.