Given a position as (x,y,z), I
 

Given a position as (x,y,z), I want the u or p value in this point by using interpolation.

Thanks all.

As a postprocessing step use t
 

As a postprocessing step use the 'sample' utility.

Inside a code use the probe functionality (See e.g. oodles/createProbes.H). This does no interpolation however.

Hi,Mattijs. I can find out the
 

Hi,Mattijs. I can find out the cell which contain the given point (x,y,z) using mesh.finCell(), then how I can know the cell's neighbour cells?

Thanks.

vector probePoint(x,y,z); lab
 

vector probePoint(x,y,z);
label probeCell = mesh.findCell(probePoint);

const labelList& probeCellNeighbours = mesh.cellCells()[probeCell];

forAll(probeCellNeighbours, cellI)
{
Do your stuff
}

But if you want to interpolate, you might want to look at the built-in interpolation classes.

Thank all. By the way, if I kn
 

Thank all. By the way, if I knew the 'label' of one cell,e.g. cellI, then I can access the field value of this cell using U[cellI]. Is that right?

Can a field loop be performed as follows:
forALL(mesh.cells(),i) {U[i]=...}
Or
forALL(U,i) {U[i]=...}?

These are simple questions. Could anybody give me a answer?

Right Both forALL(mesh.ce
 

Right

Both
forALL(mesh.cells(),i) {U[i]=...}
and
forALL(U,i) {U[i]=...}
will give you the same result, i.e. the ordering of cells and volFields are identical.

Most operations however do not require that you loop over the cells explicitly as they can be performed using field algebra.

How can get my results at the patch using points' coordinates
 

Hello,

I need the same BUT!:

I am doing a comparison between wind tunnel results and OpenFOAM simulation. Available from wind tunnel are the pressure coefficients (Cp) on 32 points. The coordinates of those points are available. I need to get P field on the body patch at those 32 points.

I mean, the coordinates of a point may not guarantee that It belongs to the patch (due to lack of accuracy of snappyHexMesh). How can get my results at the patch using points' coordinates?

HFS, were you able to find a solution to your problem? I have a similar concern. I am using stressAnalysisFoam and I need the D field on the body patch at a particular point as well.