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Fig. 8. A sample of dry sand was scanned using micro-X-ray tomography with a resolution of 60 µm. (A) The particles in a cubic section of size 3 mm are shown. The water and air distributions in this cube for different pressure conditions at the lower boundary were calculated using the Lattice-Boltzmann approach. With this method, the Navier-Stokes equation for the liquid and the gas phase are solved numerically. For a drainage process, the resulting (B) air and (C) water distributions are shown. (D) For the same applied suction during a wetting process, the water distribution is different.
