I want to do interpolation of vectors in OpenFOAM version 10. Please help me in this.

A = B + Cwhere A, Band Care vectors.

First I want to interpolate Cfrom cell centre to cell face and then after calculation of Bon the cell face the value of Awill be calculated on the cell face.

Now I want to interpolate Afrom cell face to cell centre. I want to execute this process. What commands shall I use?