The Heat and Moisture Flow, Brinkman Equations Interface
The Heat and Moisture Flow, Brinkman Equations interface models heat and moisture transport in porous media filled with liquid water air moist air.
When a Heat and Moisture Flow, Brinkman Equations () multiphysics interface is added from the Heat Transfer>Heat and Moisture Transport>Heat and Moisture Flow branch  of the Model Wizard or Add Physics windows, a Brinkman Equations interface, a Heat Transfer in Moist Porous Media interface, and a Moisture Transport in Porous Media interface are added to the Model Builder.
In addition, the Multiphysics node is added, which includes the Moisture Flow, Heat and Moisture, and Nonisothermal Flow multiphysics coupling features.
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 8-13: Modified Settings for the Heat and Moisture Flow, Brinkman Equations interface
Physics or Coupling Interface
Modified Settings (if Any)
Heat Transfer in Moist Porous Media
In the Moist Air default subfeature of Moist Porous Medium, the Absolute pressure, pA (Model Input section) and the Velocity field, ug (Heat Convection section) are automatically set to the variables from the Nonisothermal Flow multiphysics coupling feature. In the Thermodynamics, Moist Air section, the Input quantity is set to Relative humidity, and the Relative humidity, , the Relative humidity, temperature condition, , and the Relative humidity, absolute pressure condition, , are automatically set to the variables from the Heat and Moisture multiphysics coupling feature.
In the Liquid Water Properties section of the Liquid Water default subfeature of Moist Porous Medium, the Liquid water saturation, sl, and the Velocity field, liquid water, ul, are automatically set to the variables from the Heat and Moisture multiphysics coupling feature.
The latent heat sources are automatically handled on boundaries where Wet Surface or Moist Surface features are applied.
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. In the Model Input section, the Temperature, T, is automatically set to the variable from the Heat and Moisture multiphysics coupling feature.
Brinkman Equations
In the Fluid and Matrix Properties default domain feature, the Temperature, T, and the Density, ρ, are set to the variables from the Nonisothermal Flow multiphysics coupling feature, and the Dynamic viscosity, μ, is set to the variable from the Moisture Flow multiphysics coupling feature. Note that the density and viscosity are those of the moist air phase.
Moisture Flow
The Fluid flow and Moisture Transport interfaces are preselected.
Heat and Moisture
The Heat Transfer and Moisture Transport interfaces are preselected.
Nonisothermal Flow
The Fluid flow and Heat Transfer interfaces are preselected.
Note that these settings may be overridden if another predefined coupling is added.
On the Constituent Physics Interfaces
The Heat Transfer in Moist Porous Media interface provides features for modeling heat transfer by conduction, convection, and radiation. The Moist Porous Medium model, active by default in all domains, provides in addition the functionality for moisture content dependency of thermodynamics properties and latent heat effects.
The Moisture Transport in Porous Media interface provides features for modeling moisture transfer by liquid transport (capillary and convective flow), and vapor convection and diffusion. An 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 Fluid and Matrix Properties model is active by default on all domains.