Figure 15. Model geometry.
A: Radii and
of cells i and j, respectively, the sum of their spherical cap heights
and the radius
of their contact area
. B: Side view of cell i on substrate
with full cell radius
, substrate adhesion radius
, and substrate cap height
. Podium cone geometry with base radius
, podium tip radius
(
) and length
of podium m. The length is measured from half
to the center of the podium tip. C: podium position updates (contact guidance) in 2D. C1: shift of podium 1 of cell j away from podium 1 of cell i. C2: shift of podium 1 of cell k away from the body of cell i for small overlaps (analogously, for the spherical podium tip). C3: move of podium 1 of cell l towards the tangent line (T) of podium 2 of cell i if the overlapping podium exceeds the length of the tangent section (center of cell l to tangent point). The limiting line (L) between cases C2 and C3 is a spherical section. For small simulation step sizes and low cell densities C1 and C2 will generally suffice. Otherwise case C3 is employed to move a podium off another cell. However, full removal requires subsequent application of C1 or C2.
and
indicate the directional unit vector of podium 1 and 2 of cell i, respectively. The moved podia (cells j, k, l) are represented as their mid-line (dotted). Overlap between cells is defined by the intersection of this mid-line with the full podium of the respective resting cell (cell i) extended by the radius of the moved podium tip.