Environmental Engineering Reference
In-Depth Information
Figure 14.4.
Relation between capillary pressure and degree of saturation (retention curve)
To model the fluid flow we make the hypothesis that these three fluids fill the
porous space completely; see Figure 14.5. Therefore, the sum of degrees of
saturation must be equal to one:
S
o
+S
w
+S
g
= 1
[14.4]
Figure 14.5 illustrates a microscopic view of a representative volume element.
Equations of balance used in the sequel will be given at macroscopic level: they
have been obtained from analogous balance equations at microscopic level using
averaging procedures [HAS 79, LEW 98b].
Figure 14.5.
Representative volume element at microscopic level
