(a) Comparison of tortuosities (τ) estimated by the proposed model against τ obtained from syringe experiments, and a sensitivity analysis of ϕ in the proposed model. The purple lines outline the upper and lower limits. (b) Comparison of permeabilities (k) estimated by the proposed model against k obtained from syringe experiments, and a sensitivity analysis of ϕ in the proposed model. The black lines represent corresponding ratios (i.e. a ratio of the value in the vertical axis to that in the horizontal axis)