ICP=6 Leverett’s function

Leverett’s function (Leverett, 1941; Udell and Fitch, 1985)

$P_{cap}\quad=\quad-P_0\cdot\sigma(T)\cdot\ f(S_l)$

with

$\sigma$(T) - surface tension of water (supplied internally in TOUGH4)

$f(S_l)=1.417 (1 - S^*) - 2.120 (1 - S^*)^2 + 1.263 (1 - S^*)^3$

where

$S^*=(S_l-S_{lr})/(1-S_{lr})$

Parameters: $P_0$= CP(1) $S_{lr}$= CP(2)

If CP(3) ≠ 0,

$P{cgn}=P_{cap}(=P_{cgl})$

$P_{cap}(P_{cgl}）=0$