Answers: (1) OpenFOAM is a library for FVM, the choice of turbulence model, is yours. If you refer to the assumption in which the mean value theorem used to formulate FVM acts as a median filter for EXPLICIT LES MODELS, at the cell level, then yes, OpenFOAM, being thought for low-order FMV, "implements" that hypothesis; (2) The description for smoothDelta is sufficiently clear: the value of delta = (dx*dy*dz)**(1/3) in a cell does not vary more than maxDeltaRatio w.r.t its neighbouring cells