[Dazzler]

Hi Guys,


I am hoping someone can provide a little bit of advice regarding interFoam.

I am setting up a number of simulations for a couple of different circumstances but all are water based.

I need to do some investigative work/calibration on flow in pipes/channels so that i can correctly simulate pipe wall friction. I want to find out initially what impacts of using a roughWall Function are in respect of turbulent flow - and what the impacts of using meshes with different laminar layers near the surface are.

The ultimate aim is to simulate flow in a small chamber and river flow. In order to investigate the pipe roughness and compare flow to Colebrook-White values i woudl like to set up a simulation where the flow through some pipes is at constant head.

In other words i need an upper reservoir with alpha at a set level, but with no driving velocity. A constant head tank - i though that this would be relatively simple but im struggling with the boundary conditions.

If i set alpha in my tank to 1 on the walls and use setfields on the rest of the tank i can fill it up with water.

I figure i want to set the velocity on the walls as zerogradient - alpha as 1 - but i dont know what to do with the pressures. Effectively i need the hydrostatic pressure to remain constant and drive the flow - through the walls.

Every combination of boundary conditions seem to result in instability other than setting up the case with no-slip on the walls and zerogradient on the pressure - in which case the phase simply empties out of the tank - the simulation runs but this is not what i am looking for.

Any suggestions ? Do i need the GroovyBC library ?

[TobM]

Hi,

can you post a drawing of your problem? I'm not entirely sure that I understand your geometry.