intNp=floor(zPos/deltaZ);//Define the layer number with 0 corresponding to zRef. Let the z position wrt to zero, that way all z altitude are positive. (otherwise problem with volPart evaluation)
if((b->state->blockedDOFs==State::DOF_ALL)&&(zPos>s->radius))continue;// to remove contribution from the fixed particles on the sidewalls.
// Relative fluid/particle velocity using also the associated fluid vel. fluct.