TRUST capillary pressure (Narasimhan et al., 1978)
Pcap={−Pe−P0[1−SlSl−Slr]1ηfor Sl<10for Sl<1P_{cap}\quad=\quad\left\{\begin{matrix}-P_e-P_0\left[\frac{1-S_l}{S_l-S_{lr}}\right]^\frac{1}{\eta}&\mathrm{for}\;\ S_l<1\\0&\mathrm{for}\;\ S_l<1\\\end{matrix}\right.Pcap=⎩⎨⎧−Pe−P0[Sl−Slr1−Sl]η10for Sl<1for Sl<1
where
P0P_0P0 = CP(1) SlrS_{lr}Slr= CP(2) η\etaη= CP(3) PeP_ePe = CP(4)
Restrictions: CP(2) ≥ 0; CP(3) ≠ 0
