The term Qip describes the mass source from the
Interporosity Flow which is the mass transfer from the macropores to the micropores system. An additional ODE for the (passive) micropores is solved which only act as additional storage volume:
The indices M and
m stand for macropores and micropores, respectively.
θM is the volume fraction of the macropores,
Qip denotes the interporosity flow, signifying the mass transfer from the macropores (identified by index
M) to the micropores (identified by index
m).
Solving Darcy’s law for both systems entails solving two equations, each associated with dependent pressure variables pm and
pM. These equations are coupled via
Qip. From this, average quantities for the dual permeability medium as a whole are computed. The average pressure of the dual permeability medium is defined as:
Use the Unsaturated Dual Permeability Medium feature to model the transport in an unsaturated dual permeability medium where the Richards’ Equation (
Equation 4-26) describes the transport in each system.
θM is the volume fraction of the macropores,
Qip is the interporosity flow which is the mass transfer from the macroscale to the microscale system. The indices
M and
m stand for macropores and micropores, respectively.
Specify the Fluid Transfer Function αw which is used to calculate the interporosity flow, which is the mass exchange between macro- and microscale system:
with pM being the pressure within the macroscale system and
pm the pressure within the microscale system