Large-eddy simulation of a round jet in a cross-flow

A large-eddy simulation (LES) of a round jet penetrating normally into a cross-flow is described. The jet-to-cross-flow velocity ratio is 2.3 at a Reynolds number of 46,700, based on the jet bulk velocity and the jet diameter. The simulations are performed with steady and unsteady boundary conditions. A passive scalar is discretized either with a central or a TVD discretization. The results are compared with each other and the experimental measurements of Crabb, Durão and Whitelaw. The computation reproduced many phenomena present in such a flow, like the shear layer ring vortices and a counter-rotating vortex pair. In general, a reasonable agreement with the measurements was obtained. However, the calculation predicts an intense backflow low near the flat wall. As the measured points do not reach this area it is possible that such a recirculation exists but in any case the LES predicts it too high above the wall and probably too intense. The unsteady boundary condition increases the spreading of the jet slightly.