p residual doesn't come down with QUICK scheme in simplefoam
 

Dear All,

I have developed a solver based on the simplefoam solver. I have not changed anything in momentum solving, just I have added some transport equations to it.
When I use UPWIND scheme for div(phi, U) the residuals comes down to 1e-7.
Since the UPWIND scheme has some numerical diffusion I couldn't get the size of re-circulation zone correctly.
So I decided to switch to the QUICK scheme for div(phi,U). After this change the re-circulation zone becomes larger (similar to what I expect), but after the re-circulation zone some unusual vortexes appears and the residual of the p does not comes smaller than 0.01.
The fluid is water, flow is laminar and the nu is about 1e-6.

Any helps would be appreciated.
Regards