Numerical Investigation on a Dual-jet Consisting of a Plane Wall Jet and a Parallel Offset Jet at Low-Reynolds Number

Abstract

A dual-jet consisting of a wall jet and an offset jet has been numerically simulated using lattice Boltzmann method to examine the effects of jet spacing between two jet centerlines, defined as s. The Reynolds number based on jet-exit-width d is set to be Re=56 and the jet spacing is set to be less than or equal 10 times the jet-exit-width. Computational results reveal that the flow field displays periodic vortex shedding when the jet spacing is in the range of 9 ≤ s/d ≤ 10, while it remains steady with two counter-rotating vortices in the converging region when s/d ≤ 8. When s/d=9, the power spectral analyses indicate that the vortex shedding phenomenon has specific frequency. The significant oscillation stresses induced by the periodic components of velocities are found to mainly exist in the inner shear layer regions, implying stronger momentum transfer occuring in these regions.