Table 1 Geometric parameters for network specimens 1 to 4.

The viscous resistance scaled by the blood viscosity and the diffusive length scale specific to the villus (integrated ratio of exchange area over exchange distance) are determined computationally (see section S2); the total centerline length is determined through a skeletonization algorithm of the capillary network that provides vessel centerlines.

 Specimen 1 2 3 4 R/η × 107[mm−3] 7.4 3.5 27.9 28 L [mm] 8.2 11.4 15.4 17.9 Lc [mm] 2.2 1.8 2.2 2.3 L/Lc 3.7 6.5 7 7.7