[Harnoor]

I am simulating naca0012 airfoil in openfoam. I am done with the solution. I want to plot a graph of wall shear stress vs Reynolds number. I have obtained the wall shear stress along the airfoil boundary by the utility wallShearStress. Now I want to get the x coordinate of the cells along the boundary (To calculate Re) so that I can plot wall shear stress vs Re on gnuplot. I have heard that this can be done by adding some code to the solver. I am new to OpenFoam and do not know what code to add and where to add it. Please help me. Is there a simpler way to get the x coordinates? I know the cell IDs at the boundary.

Also, I have another query. I have set the prefvalue=0 and prefcell=0 in the fvSolution file. But when I go to paraview View>Selection Display Inspector and select the cell corresponding to ID 0, I find that it has a p value of -342.
Why is this discrepancy there?

Please help me. I am struck on this problem since a long time.