Hi, I'm using FLUENT for flow over an obstacle but it doesn't seem to provide satisfactory result. I'm using VOF model, the solution increasing to higher continuity. The flow velocity = 0.001 and 0.0001 m/s for air and water. I need to maintain the Reynolds number = 1 throughout the region due to thin film flow analysis and my time step = 0.001. The simulation diverging. Any suggest solving the problem.

If one of the phases is a compressible ideal gas, it is recommended that you specify it as the primary phase to improve solution stability.

I hope u have followed steps in

fluent-manual/html/ug/node937.htm

Thank you but the main problem now is the simulation halt half way. It's indicated that global gourant number to big. Any idea to solve this matter. Please help.

Global Courant Number : 26493.00

Error: Global courant number is greater than 250.0. The velocity field is probably diverging. Please check the solution and reduce the time-step if necessary. Error Object: ()