Simulation of axisymmetric round jet with and without coflow using vortex-in-cell method

Abstract

The vortex-in-cell is developed to simulate an axisymmetric round jet with and without coflow. For an incompressible and viscous jet, the method consists in three fractional steps. The first fractional step describes the convection of interacting vortex elements. The second and third fractional steps simulate the diffusion of vorticity using the diffusion velocity method and the deterministic diffusion, respectively. For the jet with no coflow, the methodology is tested by initializing the vorticity field with one vortex sheet, multiple vortex sheets and with the Stokes stream function using one and multiple vortex sheets. Two inflow profiles are tested, the top hat profile and the jet self similar profiles. The sensitivity of the results to the number of vortex elements and grid size are presented and compared. Also, the effect of perturbing the top hat inflow velocity profile is investigated. The jet with coflow is investigated using top hat inflow velocity profile with one and multiple vortex sheets. The mean centerline velocity, streamwise mean velocity profile, vorticity contour, instantaneous distribution of vortex elements, root-mean-square longitudinal and lateral velocity fluctuations, cross-stream correlation are presented. The results are compared with previous experimental measurements and numerical simulation using vortex method.