Department of Mechanical Engineering,Sharif University of Technology
Multiple square cross section jets into a cross flow at three different velocity ratios, namely 0.5, 1.0 and 1.5, have been computationally simulated, using the Large Eddy Simulation (LES) approach. The finite volume method is applied in the computational methodologies, using an unsteady SIMPLE algorithm and employing a non-uniform staggered grid. All spatial and temporal terms in the Navier-Stokes equations have been discretized using the Power Law and Crank-Nicolson schemes, respectively. Mean velocity profiles at different X-locations are compared with the existing experimental and Reynolds Averaged Navier-Stokes (RANS) computational results. Although the RANS computations require much fewer computational resources than the LES, the authors' results show reasonably good agreement with existing experimental results, rather than the computational ones. It is shown that, by increasing the velocity ratio, the jet penetration into the cross flow is increased, accompanied by a high mixing with the cross flow. In addition, the formation of counter rotating vortex pairs after the jet enters the cross flow is explained and its behavior in different YZ-planes is investigated.