Using bodyforce term look recurrent in LES. I'm trying to implement a basic LES model including a wall treatment from Schumann (1975) and I noticed that the system of equations from Thomas & Williams (1999) has a kinematic body force term 'bi' (per unit volume) included. Since the top BC is a rigid impermeable stress-free lid imposed at a height z=H, it create a region driven by body force bx(z) acting in the streamwise direction and allowed to vary with height. I tried to find some documentation in order to implement this term in OF but I didn't find much. Do you have some suggestions, documentation that I could read related to this technique implemented in OF? Thank you very much.