Heat Transfer with Surface-to-Surface Radiation
Use the Heat Transfer with Surface-to-Surface Radiation multiphysics coupling () to account for heat transfer by radiation on boundaries, when the surrounding medium does not participate in the radiation (transparent medium).
The radiosity equation defined on boundaries where surface-to-surface radiation is enabled corresponds to the radiosity method equation.
The following radiative heat source is added to the heat transfer equation on boundaries:
on the side of the boundary where the radiation is defined, where ε is the surface emissivity, G is the irradiation, and eb(T) is the blackbody hemispherical total emissive power. Where the radiation is defined on both sides, the radiative heat source is defined on both sides too.
Settings
The Label is the default multiphysics coupling feature name.
The Name is used primarily as a scope prefix for variables defined by the coupling node. Refer to such variables in expressions using the pattern <name>.<variable_name>. In order to distinguish between variables belonging to different coupling nodes or physics interfaces, the name string must be unique. Only letters, numbers, and underscores (_) are permitted in the Name field. The first character must be a letter.
The default Name (for the first multiphysics coupling feature in the model) is htrad1.
Coupled Interfaces
This section defines the physics involved in the Heat Transfer with Surface-to-Surface Radiation multiphysics coupling.
Select the Heat transfer interface associated to the temperature dependent variable. Select the Surface-to-surface radiation interface associated to the radiosity variable.
In 1D, 1D-axi, and 2D, when the Heat Transfer with Surface-to-Surface Radiation multiphysics coupling is active while solving, it disables all the out of plane features (Out-of-Plane Heat Flux, Out-of-Plane Radiation, Thickness, Cross Section) from the heat transfer interface that is selected in the multiphysics coupling. This is noticed through a warning node displayed under Compile Equations. The radiation interfaces assume an infinite medium in the out-of-plane direction, they are thus not compatible with these features.
Heat Transfer with Surface-to-Surface Radiation
Set the default opacities of the domains surrounding the boundaries where radiation is modeled.
If Default domain opacities is From heat transfer interface, the opacity depends on the domain feature:
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The Solid, Porous Medium, Biological Tissue, Building Material, and Shape Memory Alloy nodes define opaque domains.
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The Fluid and Isothermal Domain nodes define transparent domains.
Note that when a Heat Transfer in Shells interface is selected under Heat transfer in the Coupled Interfaces section, no domain node is available. Therefore, the default opacity set in the Surface-to-Surface Radiation interface is used: all surrounding domains are considered as transparent.
If Default domain opacities is Transparent, all domains are considered transparent by default.
With either option the default opacity may be overridden on each domain with the Opacity (Surface-to-Surface Radiation and Orbital Thermal Loads Interfaces) boundary node.
The opacity setting is used when the Emitted radiation direction is defined by Opacity controlled in surface-to-surface boundary features (Diffuse Mirror (Surface-to-Surface Radiation Interface), Diffuse Surface (Surface-to-Surface Radiation Interface), Prescribed Radiosity (Surface-to-Surface Radiation Interface), and Opaque Surface (Surface-to-Surface Radiation Interface)): surface-to-surface radiation propagates in non-opaque domains. Alternatively the Emitted radiation direction can be defined using the normal orientation or on both sides of boundaries. In this case this setting is ignored. Note that on boundaries where the Semitransparent Surface (Surface-to-Surface Radiation Interface) is applied, the Emitted radiation direction is Both sides, and this setting is always ignored.
Location in User Interface
Context Menus
Multiphysics>Heat Transfer with Surface-to-Surface Radiation
when a Heat Transfer interface, a Heat Transfer in Shells interface, a Slip Flow interface, or a High Mach Number Flow interface is added together with the Surface-to-Surface Radiation interface.