CFD Online Discussion Forums - How to add correcting pressure equation in SIMPLE of MRFSimpleFOAM?

Hello,
I am studying pressure correction equation in SIMPLE algorithm by OpenFOAM-1.5-dev, and now I encounter a tough problem. So, I need your help.

The SIMPLE algorithm I studied is in the solver of MRFSimpleFoam and I want to add a new pressure prediction between the mass conserving pressure correction equation and the application of under-relaxation. Actually, the new pressure is the average pressure evaluated by multidimensional averaging. Thus
http://www.cfd-online.com/Forums/mem...e-pressure.jpg……………………………………………………………….….①
Where,http://www.cfd-online.com/Forums/mem...reviours-p.jpg is a previous iteration of pressure field. http://www.cfd-online.com/Forums/mem...cture173-p.jpgis computed via pressure equation in SIMPLE of MRFSimpleFOAM. http://www.cfd-online.com/Forums/mem...re166-aver.jpgis evaluated by multidimensional averaging.http://www.cfd-online.com/Forums/mem...1-distance.jpg is the distance between the owner point and neighbor cell centers. http://www.cfd-online.com/Forums/mem...e172-nodes.jpgis the neighbor nodes

Then, the new pressure field distribution (http://www.cfd-online.com/Forums/mem...ture174-pm.jpg) is used for correcting pressure and velocity by applying the under-relaxation, and this step is the same as it in SIMPLE .
My problem is how to calculate http://www.cfd-online.com/Forums/mem...re166-aver.jpgand represents them in OpenFOAM codes.

Thanks!