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-   -   Closed tank and interFoam (https://www.cfd-online.com/Forums/openfoam/123633-closed-tank-interfoam.html)

Tobi September 17, 2013 13:13

Closed tank and interFoam
 
Hi all,

just a question to all who are using interFoam.
I made a lot of simulations with that solver but never with a closed tank or something like that.

My idea was to create a tank with p=101300 Pa in it.

I have one inlet and the rest are walls. Now I want that a fluid (water) gets into the tank with 200000 Pa.

Normally the water get in the tank till the compressed air has exact 200000Pa.

The problem I have is to set correct BC for that. Or is it possible to calculate this problem with cfd?

Due to the fact of momentum equation ... mass is going into the system but not out of the system!

Thanks in advance
Tobi

nimasam September 17, 2013 14:04

well, i guess interFoam is not suitable as it consider both phases incompressible, you may want to use compressibleInterFoam

Tobi September 17, 2013 14:35

Quote:

Originally Posted by nimasam (Post 452261)
well, i guess interFoam is not suitable as it consider both phases incompressible, you may want to use compressibleInterFoam

Oh thanks for that hint :)
thats sure!

:)

I will test it!

Tobi September 17, 2013 16:13

Hi,

okay the solver is running.

But I am not sure how I should set the BC for the inlet?


As I mentioned in the first post, the water should go inside with 2 bar while the air is with 1 bar. After compression of air to 2bar no water is going into the tank.

nimasam September 18, 2013 00:55

well, i guess i use pressureInletVelocity :), then i will fix pressure at inlet
please share the result here :)

Tobi September 19, 2013 07:05

Hi all,

well my first quess was to set U to pressureInletVelocity and p to fixedValue like you mentioned.

But it is not working. The simulations is total unphysical and I got an Floating Point exeption.

First:

p_inlet = 2 bar
P_internalField = 1 bar


Second:

p_inlet = 1.005 bar
p_internalField = 1 bar


(Nothing changed)

hmmm any hints are appreciate

nimasam September 19, 2013 07:18

at least post the error file ;), and your setup here :D

Tobi September 19, 2013 08:48

Hi,

I will do it today evening.

Tobi September 19, 2013 16:47

Here the U - file:

Code:

boundaryField
{
    wall
    {
        type            fixedValue;
        value          uniform (0 0 0);
    }

    inlet
    {
        type            pressureInletVelocity;
        value          uniform (0 0 0);
    }
}

and the p_rgh file
Code:

boundaryField
{
    wall
    {
        type            fixedFluxPressure;
        value          uniform 1e5;
    }

    inlet
    {
        type            fixedValue;
        value          uniform 1.01e5;
    }
}


nimasam September 20, 2013 02:40

1- whats your alpha1 file?
2- how is your initial setup?
3-how is your mesh?
4-which version of OF do you use?

Tobi September 20, 2013 06:24

Hi,

initialValues:
Code:


p = 1e5 (boundary = calculated)
p_rgh = 1e5
U = (0 0 0)
alphaWater = 0 (boundary = ZeroGradient for the wall and inlet = fixedValue = 1)

T = 300 (boundary = zeroGradient; inlet 300 fixed)

Mesh is a cube 0,5 x 0,5 x 0,5 m with round about 200.000 cells (not many but okay). The inlet is a extra cube with 0,05 x 0,05 x 0,05 m. Mesh made with salome only Hexaeder cells.


I think alphaWater = 1 = phase1 (water) and alphaWater = 0 = phase2 (air)

I use always the latest OpenFOAM Version (2.2.x).

nimasam September 20, 2013 06:36

what about air and water properties :), how did you setup transportproperties?

Tobi September 20, 2013 06:45

Hi,

well :D I do not have a look at that file since now. I copied the tutorial of the compressibleInterFoam solver. I thought that there is water and air included?

I will have a look at that file today evening.

Question to you - did you ever simulated a closed tank or something like that?

nimasam September 20, 2013 08:38

Quote:

Originally Posted by Tobi (Post 452705)
Hi,

well :D I do not have a look at that file since now. I copied the tutorial of the compressibleInterFoam solver. I thought that there is water and air included?

well, perfect simulation :P

Quote:

Originally Posted by Tobi (Post 452705)
I will have a look at that file today evening.

Question to you - did you ever simulated a closed tank or something like that?

nope, i never did, but as it compressible, for me those configuration seems okay :D

Tobi September 20, 2013 13:07

Hi,

as I thought everything is correct!

phase1 = water; phase2 = air.

Tobi September 22, 2013 07:45

1 Attachment(s)
Okay its working now.

But one thing is still strange (attachment)...

Does anyone know why I have so strange gradients in alpha1 ?

nimasam September 23, 2013 02:36

well
1- how did you solve your first problem (float exception?)
2- whats wrong with alpha1 gradient? distribution seems OK with me :)

Tobi September 23, 2013 02:45

Hi,

I thought that I solved the first problem :D but with a p_rgh of 2 bar at the inlet its not working anymore.

Hmmm ... I am out of mind and it is so a simple geometry... hmmm :(

cfdan September 23, 2013 10:37

don't mind to hijack this thread, but can anyone assist me here too:

http://www.cfd-online.com/Forums/ope...modelling.html

my problem seems easier to solve compared to the one here. :o


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