Figure 3.

Model including nonlinear branching, tip–tip anastomosis and the effect of varying α₁ (solid line, α₁=0; dashed line, α₁=1; dot-dashed line, α₁=10). Solutions are shown at time t=3. Values of other dimensionless parameters are as follows: δ=1 and α₂=0. The following are the numerical solution parameters: J=300, μ=0.8 and Δt=0.01, where J is the number of spatial grid points; $\mu =\mathrm{\Delta }t/\mathrm{\Delta }r$; Δt is the time-step size; and Δr is the spatial step size.