mixing layer vortices
 

Hi,

I'm a French student in the field of Fluid mechanics, and I've got some trouble with the case of create vortices in a mixing layer in a pipe with two different speed at the entrance.

In fact, I put an UDF with an tangh profile for the velocity inlet, that varies during time. the unsteady calculation always give something that create vortices.

Does someone have a tutorial for this case ? Thanks