Negative Stream Function Values - How do I get the
 

I am currently simulating stokes flow (Re = 0) in a single lid driven cavity. It is a 1m by 1m cavity where the driving wall translates at 1m/s.

As one would expect I find a main central eddy and two eddies in the corners opposite the moving wall. However these are counter-rotating and so should have a diiferent sign to the main eddy. I can only find positive values.

Does anyone have any suggestions on why I don't see these changes of sign?

There are many journal articles which back me up that these corner eddies should be negative.

Comments and suggestions would be greatfully recieved.

Re: Negative Stream Function Values - How do I get
 

It's dependent of the location of reference value(psi=0). Even though the value of small eddy is positive, I am sure that it is relatively negative compared to the value of dividing line(boundary of central eddy and corner eddy).

Sincerely, Jinwook