The Heat and Moisture Flow, Laminar Flow and Turbulent Flow Multiphysics Interfaces
The Heat and Moisture Flow interfaces model heat and moisture transport in air by laminar or turbulent flows.
When a Heat and Moisture Flow () 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, one of the Single-Phase Flow interfaces (laminar or turbulent flow), a Heat Transfer in Moist Air interface, and a Moisture Transport in air 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.
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The Laminar Flow interface () combines a Heat Transfer in Moist Air interface, a Moisture Transport in Air interface, and a Laminar Flow interface.
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The Turbulent Flow, Algebraic yPlus interface () combines a Heat Transfer in Moist Air interface, a Moisture Transport in Air interface, and a Turbulent Flow, Algebraic yPlus interface.
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The Turbulent Flow, L-VEL interface () combines a Heat Transfer in Moist Air interface, a Moisture Transport in Air interface, and a Turbulent Flow, L-VEL interface.
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The Turbulent Flow, k-ε interface () combines a Heat Transfer in Moist Air interface, a Moisture Transport in Air interface, and a Turbulent Flow, k-ε interface.
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The Turbulent Flow, Realizable k-ε interface () combines a Heat Transfer in Moist Air interface, a Moisture Transport in Air interface, and a Turbulent Flow, Realizable k-ε interface.
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The Turbulent Flow, k-ω interface () combines a Heat Transfer in Moist Air interface, a Moisture Transport in Air interface, and a Turbulent Flow, k-ω interface.
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The Turbulent Flow, SST interface () combines a Heat Transfer in Moist Air interface, a Moisture Transport in Air interface, and a Turbulent Flow, SST interface.
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The Turbulent Flow, Low Re k-ε interface () combines a Heat Transfer in Moist Air interface, a Moisture Transport in Air interface, and a Turbulent Flow, Low Re k-ε interface.
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The Turbulent Flow, Spalart-Allmaras interface () combines a Heat Transfer in Moist Air interface, a Moisture Transport in Air interface, and a Turbulent Flow, Spalart-Allmaras interface.
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The Turbulent Flow, v2-f interface () combines a Heat Transfer in Moist Air interface, a Moisture Transport in Air interface, and a Turbulent Flow, v2-f interface.
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 8-10: Modified Settings for the Moisture Flow interfaces
Physics or Coupling Interface
Modified Settings (if Any)
Heat Transfer in Moist Air
In the Model Input section of the Moist Air default domain feature, the Absolute pressure, pA, and the Velocity field, u, are automatically set to the variables from the Nonisothermal Flow multiphysics coupling feature. The Concentration, c, is automatically set to the variable from the Heat and Moisture multiphysics coupling feature.
In the Thermodynamics, Fluid section of the Moist Air default feature, the Input quantity is set to Relative humidity. 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.
The latent heat sources are automatically handled on boundaries where Wet Surface or Moist Surface features are applied.
Moisture Transport in Air
In the Model Input section of the Moist Air default domain feature, the Absolute pressure, pA, and the Velocity field, u, are automatically set to the variables from the Moisture Flow multiphysics coupling feature. The Temperature, T, is automatically set to the variable from the Heat and Moisture multiphysics coupling feature.
Laminar Flow / Turbulent Flow
In the Fluid Properties default domain feature, the Density, ρ, and the Dynamic viscosity, μ, are automatically set to the variables from the Moisture Flow multiphysics coupling feature. In addition, the Use pseudo time stepping for stationary equation form check box is automatically selected under the Advanced Settings section.
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 Air interface provides features for modeling heat transfer by conduction, convection, and radiation. A Moist Air model is active by default on all domains.
The Moisture Transport in Air interface provides features for modeling moisture transport by vapor convection and diffusion. A Moist Air model is active by default on all domains.
The Laminar Flow interface solves the Navier-Stokes equations for conservation of momentum and the continuity equation for conservation of mass. A Fluid Properties model is active by default on all domains.
The different versions of the Turbulent Flow interface solve the Reynolds averaged Navier-Stokes equations for conservation of momentum, the heat transfer equation, and the continuity equation for conservation of mass. A Fluid Properties model is active by default on all domains. Turbulence effects are modeled in different ways:
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The Turbulent Flow, Algebraic yPlus interface uses an enhanced viscosity model based on the local wall distance. The physics interface therefore includes a wall distance equation.
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The Turbulent Flow, L-VEL interface uses an enhanced viscosity model based on the local wall distance. The physics interface therefore includes a wall distance equation.
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The Turbulent Flow, k-ε interface uses the standard two-equation k-ε model with realizability constraints. Flow close to walls is modeled using wall functions.
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The Turbulent Flow, k-ω interface uses the Wilcox revised two-equation k-ω model with realizability constraints. Flow close to walls is modeled using wall functions.
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The Turbulent Flow, Low Re k-ε interface uses the AKN two-equation k-ε model with realizability constraints. The AKN model is a so-called low-Reynolds number model, which means that it resolves the flow all the way down to the wall. The AKN model depends on the distance to the closest wall. The physics interface therefore includes a wall distance equation.