Find the upstream and downstream cell

Submitted by rqwang on Thu, 10/17/2013 - 05:20

Hi CFDEMers,

I wonder whether it's possible to find the upstream and downstream cell index of a particle. I know the particle cellI is the particle's center sits.

For example, if I know the velocity at the particle center is in x positive direction, then the upstream cell is the neighbor one in negative x direction and the downstream one is the positive x direction.

Is there a good way to find the cell index? In addition, is it possible to get the velocity from the upstream one and distribute the momentum (impForces) to the downstream one? Please advise.

Thanks.
rq

Forums:

alice's picture

alice | Tue, 10/22/2013 - 08:47

Hello rq,
there is a way to access the neighbours of a cell within OpenFOAM. It requires rather deep digging inside the code... In the void fraction model IBVoidFraction this is done, accessing the data via the particle cloud (see line 212). Here the cellIDs of the specific cells are returned and can be used to determine the cells position.
There might still be simpler ways of accessing certain data, but I haven't come across them for now.
KR,
Alice

rqwang | Tue, 10/22/2013 - 23:23

Hi Alice,

Thank you for your reply. I wonder whether there is a simple way to get the cell ID given a particular position.

In openfoam, i know it's the command of "findCell". But I don't know how to use it in forceModel.
I have tried particleCloud_.mesh().findCell(position), but had no luck.
Do you have any clue?

Thanks.
rq

cgoniva's picture

cgoniva | Thu, 10/24/2013 - 14:47

Hi rq,

mesh.findCell(pos) is not the most efficent way, but should do the job...
what was the problem there?

Cheers,
Chris

rqwang | Thu, 10/24/2013 - 16:17

Hi Chris,

At last, I found I can use this command to find the cell index.
label cellUpstream = particleCloud_.locateM().findSingleCell(posUpstream,cellI);
The mesh().findCell never works and I dont know why. It says some IO stream errors.

Anyway, now the problem is half solved, but I found findSingleCell can not search the cell in a different processor after decomposed. Is it possible to access a different processor's cell index?

The left question is how to transfer the momentum from solid to fluid phase in the downstream cell. So far, I have no idea on that. Please advise.

Thanks.
rq