Macroscopic capillarity, or macrocapillarity for short,
refers to capillary phenomena occurring during
twophase and multiphase flow in porous media.
Wetting phenomena and hysteresis in porous
media are at present poorly understood in the
sense that neither in physics nor in engineering
a fully predictive theory seems to exist, that
can describe or predict all observations.
This paper extends the consitutive assumptions
of a recent approach based on the concept
of hydraulic percolation of fluid phases.
The theory proposed here allows prediction of residual
It can describe displacement processes in which
imbibition and drainage occur simultaneously.
This contrasts with the established
traditional theory where capillary forces are
lumped into capillary pressure function and relative
permeabilities, and these functions need to be
specified for each displacement process as input.
Contrary to the traditional theory the approach
advanced here allows to predict capillary pressure
saturation relations as output.