On the consistency of scale among experiments, theory, and simulation
Other literature type
McClure, James E.
Dye, Amanda L.
Miller, Cass T.
Gray, William G.
(issn: 1607-7938, eissn: 1607-7938)
arxiv: Physics::Fluid Dynamics
As a tool for addressing problems of scale, we consider an evolving approach
known as the thermodynamically constrained averaging theory (TCAT), which has
broad applicability to hydrology. We consider the case of modeling of two-fluid-phase flow in porous media, and we focus on issues of scale as they
relate to various measures of pressure, capillary pressure, and state
equations needed to produce solvable models. We apply TCAT to perform
physics-based data assimilation to understand how the internal behavior
influences the macroscale state of two-fluid porous medium systems. A
microfluidic experimental method and a lattice Boltzmann simulation method
are used to examine a key deficiency associated with standard approaches. In
a hydrologic process such as evaporation, the water content will ultimately
be reduced below the irreducible wetting-phase saturation
determined from experiments. This is problematic since the derived closure
relationships cannot predict the associated capillary pressures for these
states. We demonstrate that the irreducible wetting-phase saturation is an
artifact of the experimental design, caused by the fact that the boundary
pressure difference does not approximate the true capillary pressure. Using
averaging methods, we compute the true capillary pressure for fluid
configurations at and below the irreducible wetting-phase saturation. Results
of our analysis include a state function for the capillary pressure expressed
as a function of fluid saturation and interfacial area.