[Konstantinos]

Dear all,

To simulate the air flow in a tank I use the OpenFoam program. The tank contains water and particles.

As you can see from the attached pictures, the tank is cylindrical and half of it is full with water. For this reason I decided to use an stl file to set the water region in the setFields. I attached the setFields and the STL texts. To program setFields I use the command surfaceToCell.
My question is how can I program the setFields text in order to set a portion of the tank to be water.
I have also attached the results.

Thank you in advance for your help.
With Kind Regards,
Konstantinos

[Ship Designer]

Hello Konstantinos,

As far as I know it is not necessary that in the setFieldsDict the volume matches exactly the one of your geometry file. I assume that in your case the domain has the shape of the tank's interior. In that case you can more simply define a box that is bigger than the domain and intersects it at the desired fluid level for setting the liquid phase. In essence, the boolean union between the box and the domain will get the cells in the field set to 1. See my suggestion below. I hope I got the coordinates right, I'm used to having z pointing upwards. With this in mind, make sure that g also points in the right direction.

...
FoamFile
{
    version     2.0;
    format      ascii;
    class       dictionary;
    location    "system";
    object      setFieldsDict;
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
defaultFieldValues
(
    //volScalarFieldValue alpha.air 1  
    // It is typical to define this the other way around,
    // air = 0 and water = 1.
    // First set the entire domain to 0.
    volScalarFieldValue alpha.water 0
);

// Then only set to 1 what needs to be filled with the liquid phase.
regions
(
    boxToCell
    {
        box (-5 -10 -5) (5 0 5);        
        fieldValues
        (
            volScalarFieldValue alpha.water 1
        );
    }

    // If needed for the boundary conditions, do the same with faces
    boxToFace
    {
        box (-5 -10 -5) (5 0 5);        
        fieldValues
        (
            volScalarFieldValue alpha.water 1
        );
    }
);
// ************************************************************************* //

Hope this helps and if in doubt, check out the multiphase tutorials to see how they initialize the phases.

Cheers, Claudio

[Konstantinos]

Dear Claudio,
Thank you for your help.
With Kind Regards,
Konstantinos