I am having a problem trying to get the Reynolds stresses to converge in a problem which is modelling the flow of an incompressible fluid.

All they are doing is oscillating.

Does anyone have any suggestions?

DAE

my friend u will have a lot problem with this model. u can have very good results by others models in compressible flow. if u have to work with this model at first u must use other models and at last use this model.

I don't know what is your case but, here I go. First try to use a first order differencing scheme (UPWIND) for all variables with false timestepping (if you're running on steady state). Relaxation factors are also something to take care. Are you using a commercial or your own code?

Good luck, cfd guy