Interpolation of pressure gradient

Submitted by jhofman on Fri, 09/11/2015 - 18:07

Hi!

I recently started using CFDEMSolverPiso and I noticed something about the implementation of the fluid pressure gradient.

In gradPForce.C the gradient is calculated explicitly, followed by a cellPoint interpolation to the particle position (if interpolation is turned on), however, this gradient is calculated according to the logic of OpenFOAM (Gauss linear interpolation) which means:

if we have a pressure like this:
0 | 0 | 100 | 0 | 0

we obtain a gradient like this:
0 | 50 | 0 | -50 | 0

and doing a cellPoint interpolation will show that the gradient is largest at the cell-center of the 2nd and 4th cell, which, from the original pressure distribution, seems wrong.

How is this justified?