[Lupocci]

Dear all,
I am interested in completely understand how boundary conditions work with the porous FAVOR approach. I read all the manual of version 9.2 and also the Hirt and Sicilian paper on the FAVOR method ( http://www.flow3d.com/pdfs/tp/mariti...acles-3-85.pdf ) . This paper at pag 13 says: "a simple device is required. the difference espressions for all fluxes are formulated in terms of velocity derivatives. Then, all the derivatives at interfaces are set to zero. In this way all boundaries become free-slip boundaries. (When viscous shear stresses are wanted they can be adds a separate force contributions.)"
So I this the way BCs are currently implemented in flow3D? How can you transform the fluxes in velocity derivatives?And how do you prescribe the shear stress? In which direction? Is the direction of the wall known or not? It does not seems to me that a reconstruction is done in orderto compute the direction of the the wall. What if it is moving and it is compressible? you need to reconstruct the interface as in VOF right? All this is not explained in the paper or in the manual.
Thanks
A.