In case you are dealing with sharp fields, there are multiple options to choose from. Usually, the literature recommends the "least squares approach", or linear regression. In order to get somewhere with this, the least squares points should pick up the skew cells
, not just the normal own-nei surrounding cells in OpenFOAM. Still, there is a workaround that works fine:
#1) IDW interpolation of cell values to mesh points
#2) create a surface*field
#3) average the...