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Fig. 9. Dry sand samples were mapped with synchrotron radiation tomography (left: HASYLAB, right: SLS). Particles are shown in black. The sizes of the particles range (A and C) from 300 to 900 µm and (B and D) from 100 to 200 µm. (A and B) First, the pore sizes for all voxels of the pore space were determined. Bright values indicate large pore sizes. A small section indicated by the white border is enlarged to explain the determination of the pore size. First, the distance from the solid phase is calculated (A1). This distance corresponds to the radius of a sphere. A voxel of the pore space can be an element of different spheres and the radius of the largest sphere determines the pore size of the voxel (A2). The grid shows the size of the voxels. In the bottom row, the water (gray) and air (white) distributions computed with a morphological pore network model are shown. A head of (C) –15 cm and (D) –50 cm was applied at the lower boundary in the numerical experiment. The computed water saturation of the pore space was 56% for the coarse sand and 49% for the fine sand.
