[Akshay_11235]

Hello everyone,


I have been stuck with a problem for a while now. The problem involves free surface flow under the influence of gravity. As described in the picture (see attachment), the water level difference should drive the flow downstream. I am using interFoam to investigate such flows.



I cannot figure out what inlet boundary conditions should be used for


1. p_rgh
2. U
3. alpha.air and alpha.water


The way I would like to setup the problem is as follows:


Specify an initial water level (using setFields). I do not know the mass flow rate or the velocity at the inlet. I would like OpenFOAM to compute the velocity or/and mass flow rate at the inlet. This should be possible as the flow is pressure driven. The only information I provide at the inlet is the initial water level (pressure). At the downstream I would like to set either zeroGradient (outflow) or a specified water level (using setFields).



I have tried a few combinations for the inlet boundary conditions. However, nothing seems to be working. The deltaT simply keeps on decreasing. I am aware that this is due to ill-defined boundary conditions. However, Using this setup as described above, I have no idea which boundary condition to employ as the inlet face.



I know that this is fundamentally possible as Ansys-Fluent has an option of Open Channel Flow where you can provide the water surface elevation, bottom reference, and inlet velocity (as 0) and it initiates the solution. I would like to know if this is possible in OpenFOAM. If yes, what boundary conditions should be used at the inlet.



I am quite sure that its the inlet boundary condition that is causing the problem.



Any help will be appreaciated.