[rakesh927]

Hi friends,

I would like to simulate a steadystate flow of water in a tub (open to atmosphere and filled with stones to some depth), in which water enters through an inlet pipe and leaves through an outlet pipe.
I could simulate this case using interFoam solver (two phases, air and water) which is transient. It takes lot of time for the solver before the water level reaches the outlet height.

I want to solve this in steady state. Kindly help me out in selecting the solver.

Thanks

Rakesh

[floquation]

Originally Posted by rakesh927

It takes lot of time for the solver before the water level reaches the outlet height.

Quick suggestion:
Can't you use "setFieldsDict" to set an initial water height in your system, such that you do not need to wait as long?

[rakesh927]

Thank you Kevin,

I almost forgot this option :P. One more question: after I get near steady U field of water phase, is it possible to use this for adding into scalar transportFoam?

Thank you.

[Dipsomaniac]

Originally Posted by rakesh927

Thank you Kevin,

I almost forgot this option :P. One more question: after I get near steady U field of water phase, is it possible to use this for adding into scalar transportFoam?

Thank you.

Hi Rakesh

Have a look at the following tutorial by Tobias Holzmann using interFoam with a scalar transport equation added as function in the controlDict file.

http://www.holzmann-cfd.de/index.php...oscillator-vof

Cheers,
Brian

[rakesh927]

Thanks Brian Going through the content, very useful.

[rakesh927]

Originally Posted by floquation

Quick suggestion:
Can't you use "setFieldsDict" to set an initial water height in your system, such that you do not need to wait as long?

Hi friends,

But my question about solving multiphase flows in steady-state remains unanswered. The case I was talking about, contains a tub filled with stones, water enters from inlet and leaves through outlet, tub is exposed to atmosphere and contains air [water is exposed to atmosphere]. Eventually I would like to simulate the transport of multiple chemicals and their interaction / decay reactions.
As suggested by Kevin, I can set the initial water levels for quickly attaining the near steady state flow conditions, but for solving the transport of chemicals I have to run the interFoam for each time step [which is computationally intensive].
Is there a way to extract velocity field of water from interFoam and plug that into transportFoam?

Thanks

PS: I am relatively new to OpenFoam, I may sound little immature in posing my questions.

[Dipsomaniac]

The scalarTransportFoam solver only solves a passive scalar transport equation and uses the initial velocity field supplied at start, without recalculating it, hence if you take a steady state velocity field from your multiphase simulation, you could use that as the initial velocity field in the scalarTransportFoam solver. Difficulties come with respect to transport of the scalar across the interface, as the scalarTransportFoam assumes it a single phase system.

For extracting just the velocity of the water phase, you could do that in paraview by using the alpha values as a switch, e.g. U*(1-alpha)(alpha),would either give you just the velocity field of the liquid or gas depending on your setup,or program it as a function directly into your control dict as a user defined function.

[rakesh927]

Hi Brian,

I have done something similar to what you have suggested, created a new velocity field V in which values are filled from U field as it is for alpha values >= 0.5 [where alpha=1 for water and =0 for air] and assigned values 0 for alpha<0.5. So that V field contains velocity values for water phase only and rest zeros.
This approach seems to work, however, if diffusion is significant, the pollutants transport into the space where zero velocities are assigned [technically where alpha<0.5, or air phase] which is not satisfactory.

Hope you understand me.

Kindly help me out. Thanks