hi, i need to simulate a circular jet impingement on a flat plane. i tried using a 2D axisymmetrical configuration, but it didnt work. Now, i am trying to design a 3D model, it is fairly easy, but i wanna keep the number of elements in gambit below 2.5 million. does anyone have any suggestion in general? i need a big model to use pressure far field, because i used pressure outlet and got more than 17 thousand reversed flow, and of course,i didnt converged appropriately. thanks.

2D axisymmetrical configuration works perfectly. For both 2D and 3D simulations, use fine mesh near ground plane and also near the edges of the circular jet pipe. Use pressure Boundary conditions. Also it is better to post your real name instead of pseudo ones.

what are you trying to model? a supersonic jet impingement case or a subsonic one?

you are bound to get reversed flow on the pressure utlets as the flow exiting your domain through the pressure outlet will set up a slight recirculation zone (magnitudes of velocity are orders smaller than the mean jet flow). it should not affect convergence though. it might also be useful to decide what property is best utilised for convergence, we have found good acceptance with literature (supersonic jet impingement case)when using the pressure outlet mass flow as a convergence criterian. pertubations in shear layers in the case of the supersonic impingement always pose problems in getting all residuals to converge to the set convergence criterian.

nandu