[Tempest]

Dear foamers,

How can I calculate drag coefficient for porous zone without using forceCoeffs macro in controlDict.

One option is to take the difference of average pressure at the front and rear face of the body for pressure drag. And for viscous drag difference of du/dy at top and bottom face of body.

I can extract pressure values by using sampleDict. But I am not able to extract du/dy.

I am defining volTensorField gradU = fvc::grad(U)

volScalarField dUdy = gradU.component(tensor::YY)

But I am not sure this is correct. Please help me out here.

[hiuluom]

1. You can extract porous region by using foamToVTk.

you can refer the link here. How to visualize cellset region in OF?

2. Using paraview to openfoam porous region and then refer the link to calculate the force:

https://www.simscale.com/docs/conten...ce-computation

[pantalaimon]

Hi,

I am attempting to compute the forces on a porous sphere in laminar flow conditions using OF.

I can produce the flow field fine, and I can compute the porous forces within the porous sphere via controlDict, specifying the cellZone. However the forces that I am interested in are the non-porous drag forces: i.e., the drag forces due to the delta pressure on the front and rear of the sphere and skin friction, which are derived from variables outside the cellZone.

I thought that I could follow the above suggestions. In paraview, it's easy to view the cellZone by itself, as per the first suggestion. However, paraview seems to be unable to "Generate Surface Normals" for the cellZone as suggested here.

Does this feature only work with cellSets, as per tutorial, or has anyone got it working for cellZones?

Or indeed, has anyone a different suggestion for the computation of the (non-porous) drag force on a porous body?

Cheers!

[mechy]

Originally Posted by pantalaimon

Hi,

I am attempting to compute the forces on a porous sphere in laminar flow conditions using OF.

I can produce the flow field fine, and I can compute the porous forces within the porous sphere via controlDict, specifying the cellZone. However the forces that I am interested in are the non-porous drag forces: i.e., the drag forces due to the delta pressure on the front and rear of the sphere and skin friction, which are derived from variables outside the cellZone.

I thought that I could follow the above suggestions. In paraview, it's easy to view the cellZone by itself, as per the first suggestion. However, paraview seems to be unable to "Generate Surface Normals" for the cellZone as suggested here.

Does this feature only work with cellSets, as per tutorial, or has anyone got it working for cellZones?

Or indeed, has anyone a different suggestion for the computation of the (non-porous) drag force on a porous body?

Cheers!

Hello
Dear pantalaimon
I have the same problem
do you find it's solution ?

Best Regards

[zeinelserfy]

does anyine find a solution for that case?