I am modelling ink impact and absorption in porous media and I was looking at the influence of the grid size on the solution. Refining the grid at first gave similar results (up to 1e-3 s), but as I increased computation time (1e-2 to 1 s) the fine grid ink droplets show sooner equilibrium state than coarse grids. Moreover the absorption and spreading in coarser grids keep continuing in time. Why is this happening? Marjon

hmmm, not sure. What numerical options (e.g., implicit/explicit) and physical models (surface tension, flow losses in porous medial, capipllary pressure) are you using?