Background (absolute) face transmissibility of particular face.
Detailed Description
Internal class to manage the direct and derived quantities needed to formulate the fluid transport system.
Note: This class elides off-diagonal elements of the phase mobility Jacobian, . These elements are assumed to be strictly equal to zero. In other words, the relative permeability of phase is assumed to depend only on the saturation of phase . This convention allows storing only the two diagonals of the mobility Jacobian per grid cell.
The static gravity term is the scalar value
in which i is the half face index corresponding to the cell-face pair (f,c) and is the absolute (bacground) two-point transmissibility of face f.
The fluid transport problem is formulated in terms of saturation changes, , per cell. These changes are the primary degrees of freedom in this model.
Capillary pressures are defined by the fluid model, but usually correspond to (e.g., ).