[alsdia]

Hello,

I was making a comparison between StarCCM+ and simpleFOAM using a sphere.
In simpleFoam dimensions of pressure become pressure divided by density.
But I would like to obtain in Paraview a plot with the real pressures.

1) is there a way in Paraview to multiply all the pressure field by the density?
or
2) is it possible to customize simpleFOAM in such a way that before results are written, all pressures are multiplied by the density? Which file should be modified simpleFoam.C or createFields.H or something else and how?
or other ideas?

-----------------------------------------------------------------------------------------------------------------------
reference
(http://openfoamwiki.net/index.php/Ma...ble_solvers.3F
=> simpleFoam sphere max pressure * 1.205 = 106.399 * 1.205 =128.2108Pa ~ 129.1Pa of StarCCM)
sphere case @
https://www.dropbox.com/sh/gg1ypj0c1...vYI_k/OpenFOAM

[sail]

Originally Posted by alsdia

Hello,

1) is there a way in Paraview to multiply all the pressure field by the density?
or

add the filter calculator, there you can multiply your pressure by the density

[vinayvm]

So the pressure p we see in paraview is indeed p divided by density for the simulations done in OpenFOAM.

Can someone confirm this?

Thanks.

[Lorena2fdez]

Originally Posted by vinayvm

So the pressure p we see in paraview is indeed p divided by density for the simulations done in OpenFOAM.

Can someone confirm this?

Thanks.

When a variable is defined in OpenFOAM there must be indicated the dimensions of this variable. For an example of p:

FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    location    "0.2";
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [1 -1 -2 0 0 0 0];
#....

The numbers are the exponent that we have for each dimension. The place of the numbers is associated with the dimensions specified below:

Nº Property Dimension
1 Mass kg
2 Length m
3 Time s
4 Temperature K
5 Quantity mol
6 Current A
7 Luminous intensity cd

And for the previous case of p we have the units [kg / (m*s²) = Pa].

Best regards,
Lorena

[vinayvm]

Thanks for your reply Lorena2fdez

My p file looks something as follows:

FoamFile
{
    version     2.0;
    format      ascii;
    class       volScalarField;
    object      p;
}
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 2 -2 0 0 0 0];

internalField   uniform 0;

I thought eventually it gave output in Pascal which is correct pressure unit.