Experimental Study of Flow Oscillation Phenomenon in Right-Angle Branch with Double Side Branch

In the previous study, it was clarified in the right-angle branch with single side branch that the velocity periodically oscillates in the side branch, and the Strouhal number is independent of cross-sectional area ratio, the flow division ratio of side branch to main branch, and the Reynolds number. In the present study, the flow structure in the right-angle branch with double side branch has been experimentally studied in laminar steady flow using laser Doppler anemometry and particle image velocimetry. Consequently, the velocity also oscillates periodically in both side branches, and the Strouhal number is independent of the Reynolds number although the Strouhal number in the downstream side branch is a little larger than that in the upstream side branch. It has been clarified that the flow oscillation in the right-angle branch is a characteristic phenomenon caused from its geometry and the factor inducing oscillation would be high shear rate.