Numerical Simulation of a Compound Round Jet by Three-Dimensional Vortex Method

A jet issuing with velocity U₀ from a round nozzle of diameter D into the same fluid co-flowing with velocity U_a is simulated by the three-dimensional vortex method. The velocity ratio U_a/U₀ is 0.27, while the Reynolds number based on U₀ and D is 5.5×10⁴. The number of vortex elements drastically increases in the region where the stretch and contraction of the vortex element occur due to the appearance of turbulence. When applying the core distribution function proposed by Winkelmans and Leonard, the time-averaged velocity successfully satisfies the self-preservation distribution, and the axial component of the turbulent intensity almost agrees with the experimental result. The Reynolds shear stress takes its maximum value at the periphery of the jet in accordance with the experimental result, though it is higher than the experiment.