The Moisture Flow, Brinkman Equations Multiphysics Interface
This version of the Moisture Flow interface models moisture transport in the gas phase of a moist porous medium, by vapor diffusion and convection. When a Moisture Flow, Porous Media Flow () multiphysics interface is added from the Chemical Species Transport > Moisture Flow branch () of the Model Wizard or Add Physics window, a Brinkman Equations interface and a Equilibrium Moisture Transport in Porous Media interface are added to the Model Builder.
In addition, the Multiphysics node is added, which includes the Moisture Flow multiphysics coupling feature.
The Multiphysics Branch in the COMSOL Multiphysics Reference Manual.
Stationary and time-domain modeling are supported in all space dimensions.
Settings for the Physics Interfaces and Coupling Features
When physics interfaces are added using the predefined couplings, specific settings are included with the physics interfaces and the coupling feature.
Table 8-12: Modified Settings for the Moisture Flow, Brinkman Equations interface.
Physics or Coupling Interface
Modified Settings (if Any)
Equilibrium Moisture Transport in Porous Media
In the Hygroscopic Porous Medium default domain feature, the Absolute pressure, pA (Model Input section) and the Velocity field, ug (Moist Air Properties section) are automatically set to the variables from the Moisture Flow multiphysics coupling feature.
Brinkman Equations
In the Porous Medium default domain feature, the Density, ρ, the Dynamic viscosity, μ (both in Fluid Properties section), the Porosity, ε, and the Permeability, κ (both in Matrix Properties section) are automatically set to the moist air variables from the Moisture Flow multiphysics coupling feature.
Moisture Flow
The Fluid flow and Moisture Transport interfaces are preselected
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Note that these settings may be overridden if another predefined coupling is added.
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The relative moist air permeability κrg is set in Equilibrium Moisture Transport in Porous Media > Hygroscopic Porous Medium > Moist Air (Moist Air Properties section).
On the Constituent Physics Interfaces
The Equilibrium Moisture Transport in Porous Media interface provides features for modeling moisture transport in media filled with moist air and liquid water, with a time-dependent liquid saturation. Transport is done by vapor convection and diffusion in the gas phase, and convection and capillarity in the liquid water phase. A Hygroscopic Porous Medium model is active by default on all domains.
The Brinkman Equations interface computes the fluid velocity and pressure fields of a single-phase flow in porous media in the laminar flow regime. A Porous Medium model is active by default on all domains.