(a) Plot of minimum vascular volume fraction vs scaffold thickness L. [(b) and (c)] Plots of vascular diameter D and spacing H vs L for the optimized models in (a). For all models, ΔP=20 cm H2O, η=0.7 cP, K=10−10 cm4∕dyn s, qO2=10−8 mol∕cm3 s, and kO2=1.2×10−9 mol∕cm3 mm Hg. Red curves denote data from Figs. 34 in which L is scaled by (η∕0.7 cP)×(20 cm H2O∕ΔP).