Incompressible LES mixing in a T junction

bramdejager

Dear all,

Running a transient simulation of mixing in a T junction using the Oodles solver extended with a passive scalar, the velocity field shows checkerboard oscillations.

These oscillations occur in the two inlet ducts before the mixing zone. Downstream the mixing zone the velocity seems smooth (but of course turbulent).

I use the linear scheme for div(phi,U) and the other div schemes are set to limitedLinear. The mesh is built of hexahedrals, while the time step is such that Co_max = 1.4 or something. Co_mean is 0.2.

Regarding the extended oodles solver: I did not change any solution algoritm.

Anyone having a clue?

Many thanks,

Bram