Opacity (Surface-to-Surface Radiation and Orbital Thermal Loads Interfaces)
This node enables to define the surface-to-surface radiation direction on boundaries surrounding the domains where it is defined. When several spectral bands are defined, the opacity can be set for all or only a selection of wavelengths.
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), Opaque Surface (Surface-to-Surface Radiation Interface)), surface-to-surface radiation propagates in nonopaque domains. Alternatively the Emitted radiation direction can be defined using the normal orientation or on both sides of boundaries. In this case the Opacity node 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 the Opacity node is ignored.
By default, all the domains and the exterior of the Surface-to-Surface Radiation interface are considered as transparent. To set the exterior as opaque, change the Selection of the Opacity node to All voids in the Domain Selection section, and set it as Opaque. Depending on the geometry, an infinite void and several finite voids may be available for the selection. When the Heat Transfer with Surface-to-Surface Radiation multiphysics coupling is active, it controls the default opacity.
Opacity
Depending on the Wavelength dependence of radiative properties defined in the Radiation Settings section of the physics interface settings, different sections display underneath.
When Wavelength dependence of radiative properties is set to Constant, select Opaque (default) or Transparent to set the domain’s opacity type.
When Wavelength dependence of radiative properties is set to Solar and ambient or Multiple spectral bands:
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When Opacity is set to User defined for all bands (default), set the opacity of the domain for all bands by selecting Opaque (default) or Transparent. Use this option if the transparency or opacity properties of the material are not wavelength dependent.
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When Opacity is set to User defined for each band, set the opacity for each spectral band by selecting the corresponding check box in the Opaque column of the table. By default the check box is selected for all spectral bands. Defining an opacity for each spectral band makes it possible to build models where the transparency or opacity properties of the material defers between spectral bands.
Free Convection in a Light Bulb: Application Library path Heat_Transfer_Module/Thermal_Radiation/light_bulb
Thermo-Photo-Voltaic Cell: Application Library path Heat_Transfer_Module/Thermal_Radiation/tpv_cell
Location in User Interface
Context Menus
Surface-to-Surface Radiation>Opacity
Ribbon
Physics tab with Surface-to-Surface Radiation selected in the model tree:
Domains>Opacity