[MDPrasad]

Hai all,
I am trying solve the case flow through a convergent section using SIMPLE algorithm(two inclined flat plate). I am using the discretization scheme for unstructured mesh given by Dr. Murthy and Dr. Mathur. For convective terms i am using first order upwind scheme at pertinent locations. The code gives a converged solution for high viscosity values (10^-3). But as the viscosity decreases (10^-5), the solution starts oscillating and starts diverging. The same combination of schemes was used in FLUENT, and it gives a converged solution in very less number of iterations (for low viscosity).
As convergence is obtained at low viscosity values, the implementation has to be correct. What could be other reasons for oscillations. I am working on this for the past two weeks, but still unable find the reason for oscillations (at low viscosity). The flow is assumed to be incompressible.

thanks in advance for the help.