[prashanthreddyh]

I am simulating an open channel (free surface flow) flow problem using FLUENT 3DDP. This problem is a levee breach problem. Water flowing in a open channel and there is a breach in the channel. Downstream end of the channel is closed and all the water flowing out through breach and flooding the area adjacent to the channel. I am modeling this problem as a steady state problem. I know amount of water entering into the channel and upstream depth but dont know the downstream depth. Amount of water going out (equal to water coming in) is known but it flowing in three directions and flow distribution is not known. Most of the flow is subcritical

My mesh quality is OK. turbulence model is k-epsillon. convergence criteria is massflow at inlet and outlet matching.

I have few questions
1. How to set the boundary conditions for this problem?
2. I have taken mass flow inlet and pressure outlent (I dont know exact depth at outlet but assumed a trial value) boundary conditions and when I compare the simulated and experimental velocity profiles are not exactly matching. how to improve the results ( I mean how to fine tuning FLUENT constants wall roughness, turbulence parameters etc.).

3. I would like to set dy/dx (depth gradient) is zero at the OUTLET boundary but How to set this bc.

4. Some of the Fluent simulations (in the literature) either far upstream or far downstream boundary conditions are taken. Can it helpful to me.

Thank you and I appreciate your kind help answering these questions.

with regards
Prashanth