The boundary conditions and associated Heat parameters are specified as follows:

• Geometric Entities Panel > Boundaries > [Desired Boundary]
• Properties Panel > Model Tab > Heat

This is a thermal boundary condition in which the heat flux is set to zero (as if insulated).

The Adiabatic Boundary Condition is the default condition for the Heat module when a Wall or Rotating Wall boundary condition is selected for the Flow module .

This is used whenever the temperature at a boundary is known.

The Specified Temperature is the default boundary condition when a Specified Velocity, Specified Volumetric Flux, Specified Total Pressure or Specified Pressure Inlet is selected for the Flow module. The temperature of any fluid exiting the domain is based on the internal (upwind) temperature. The temperature of any fluid entering the domain is based on the Specified Temperature. In addition to any convective effects, it influences the internal temperature via conduction.

This is used whenever the total temperature at a boundary is known. The temperature of any fluid exiting the domain is based on the internal (upwind) temperature. The temperature of any fluid entering the domain is based on the Specify Total Temperature. In addition to any convective effect, this temperature influences the internal temperature via conduction.

This is used at an opening where flow is expected to exit the domain. In case of back flow, the temperature of the incoming fluid is specified by the User Specified or Fully Developed under Back Flow Option:

• Fully Developed: The temperature of any fluid re-entering the domain is based on the cell center temperatures of the faces which make up the outlet boundary.

• User Specified: The temperature of any fluid re-entering the domain is based on the Temperature specified.

This implies that there is no heat flux or temperature gradient normal to the boundary. Symmetry for the Heat module is the same as the Adiabatic boundary condition. This usually corresponds to a physical symmetry in the model, but it doesn’t have to, as long as the effects of this boundary condition make sense.

This is used to specify the heat flux per area on the boundary. This allows specifying heat flux as a function of location (using Expression Editor).

The direction of the heat flow is decided using these options:

1. Inflow: Imposes a positive temperature gradient in the direction into the domain. Specify the heat flux at Value.

2. Outflow: Imposes a positive temperature gradient in the direction out of the domain. Specify the heat flux at Value.

3. Both: Allows heat both into (negative value) and out of the domain (positive value). Specify the heat flux at Value.

This is used to specify the total heat flux on a boundary. The specified Value is uniformly distributed (by area) across the boundary. The heat flux for each cell face on the boundary is calculated as follows:

5.399

The direction of the heat flow is decided using these options: Inflow, Outflow, or Both.

• Convection: Requires specifying the values for Exchange Coefficient and Convection Ambient Temperature under the expanded list of Options.

• Convection/Radiation: This allows to specify both Radiation and Convection processes. This requires specifying the values for Exchange Coefficient, Convection Ambient Temperature, Emissivity, and Radiation Ambient Temperature under the expanded list of Options.

   

• Radiation: This requires specifying the values for Emissivity and Radiation Ambient Temperature under the expanded list of Options.