Simulation of the effect of pulsatile flow on flow features dynamics during abrupt contraction into two parallel rectangular jets

Abstract

The analysis of the converging region of two parallel jets under unsteady flow conditions is important in its design and safety. Numerical simulation was used to investigate the flow features before the contraction plane. Pulsatile flows with a fixed flow period of 5 s, mean flow velocities between 0.033–0.045 m/s, and flow amplitudes of 0.2–0.4 were simulated in this study. The changes at the contraction were characterized by repeated changes in the velocity profile, recirculation area, and corner vortices. The velocity profile in the contraction region remains axisymmetric throughout the cycle of pulsation. The corner vortices increased with a decrease in the mean velocity when the vortex length was longer than the length from the corner to the stagnation point but began to reduce when the mean velocity started increasing in the pulsation cycle. The results provide more explanation of flow feature characteristics at channel corners and abrupt contraction planes.