[adasin]

Hi,
Is it possible to calculate the cl and cd on the surface generated by immersed boundary method, in paraview? I have pressure value all over the surface.

[amin.adibipoor]

Originally Posted by louisgag

In 2D, you might want to try something like this in paraview on the surfaces you want to evaluate,

1. filter: generate surface normals (disable splitting, activate compute cell normals)
2. filter: calculator using something like this for moments : Normals_Y*p*yourDensity*(yourCoRx-16) + Normals_X*p*yourDensity*(yourCoRy-coordsY) replacing yourDensity and yourCoR* by appropriate values or simplify it to get forces
3. filter: integrate variables and look for the results of the integration in the table that appears

in the end this procedure gives you sum_cells(P*rho*A*norm_y)

I think this can be easily adapted to 3D.

cheers

Hi
Thanks for the tip
Only one question
What do you mean ba "yourDensity"? Body or water?

[louisgag]

The fluid, obviously, as you are looking for the forces exerted by it and using it's pressure...

[CHAYANIT]

Are you not considering velocity in coefficients calculation?

[louisgag]

Chayanit Nigaltia:


the formulas I gave give force/moment values.
If you want a specific coefficient you have to compute it from there.

[Md. Rakib Hossain]

Originally Posted by scott

I found a solution:

Extract Surfaces
Generate Surface Normals
Use the calculator to multiply pressure by the surface normals (Normals*p)

This then prints the values in the data tab at the right in three columns, one for each normal direction.

I then integrate these to get total forces on the area using Integrate Variables.

Let me know if you see any problems with this approach!

Cheers,

Scott

I just follow this procedure but the x component of force i.e. drag force shows a negative value.
Can you help?

[rajesh1155]

hi,
i getting drag coefficient 0.4066 and the drag force is 0.3411 N but by manual calculation i m getting 0.06N
please help me on this.