Figure 4: Computer model of the cell population in the 3D channel structure of the Ta scaffold. (a) Cross section of the perfusion reactor with the two cell-populated Ta scaffolds inside. The simulation box is located in the center of the figure. The porous channel structure of the scaffold is modeled by interconnected spherical cavities whose walls are occupied by cells. (b) Double-walled cavity with connections to adjacent cavities. The narrow region between the inner and the outer wall represents the cell-populated area. (c) Construction of the channel structure from many cavities. (d) Lower part of the simulation box consists of the cross section though the Ta disk and the medium reservoir are below the disk. Periodic boundary conditions are assumed (see text for details).