[pippo2013]

Dear Foamers,

I am modelling the fluid flow inside a rotatig sphere. In order to represent the effect of a thin liquid layer, covering a small portion of the solid boundary,
I would like to implement a BC derived from Couette flow assumption, hence impose a tangential stress equal to mu*U/h , where U is the velocity at the wall and h is the width of the thin layer.
(see pag. 129 of http://www.dicca.unige.it/bottaro/fm...M_LaSpezia.pdf)

Which BC is easier to modify and how?

Could you please give me some hints?
Thanks a lot