Thermo-Optical Properties - Advanced dialog box (Thermal/SST/ESC/Multiphysics)

Option	Description
Name	Specify a meaningful name for the modeling object.
Label	Specify a unique numeric identifier for the modeling object.
Description	Specify a description for the modeling object.
Properties
Type	Gray lets you specify infrared thermo-optical properties and solar thermo-optical properties uniformly across their respective spectrums.Non-Gray — Wavelength Dependent lets you specify thermo-optical properties as a function of wavelength.
Infrared Properties
Appears when Type is set to Gray.
Specify Method	Emissivity lets you define infrared emissivity required for all thermal radiation simulations.BRDF lets you define diffuse bidirectional reflectance as varying with angle of incidence and angle of reflection measured from the element's normal.
Emissivity	Defines emissivity as a constant value or variable with temperature or the angle of incidence measured from the element's normal. For more information, see Additional magnitude options.
Diffuse Bi-Directional Reflectance****Specify Field	Appears only when you select BRDF from the Specify Method list.Lets you specify the variation of diffuse bidirectional reflectance with angle of incidence (theta) and angle of reflection (phi).
Specular Reflectivity	Defines infrared specular reflectivity. Infrared specular reflectivity is required for modeling surfaces that are specular for infrared radiation.For more information, see Additional magnitude options.
Transmissivity	Defines the transmissivity thermo-optical property as a constant value or that varies with direction of incidence (theta) and angle of incidence (phi). Transmissivity is the fraction of incident light that passes through an object.Note: When you specify different transmissivity values for top and bottom thermo-optical modeling objects, Simcenter 3D Thermal always uses the transmissivity value of the top side only.This is because the transmissivity is a property of the material, not a property of the surface, as for example, emissivity. For more information, see Additional magnitude options.
Solar Properties
Appears when Type is set to Gray.The solar thermo-optical properties are required when you use the Solar Heating Space, Solar Heating, Radiative Heating, and Orbital Heating simulation objects.
Specify Method	Absorptivity lets you define solar absorptivity to account for scattering of incident solar spectrum radiation. BRDF lets you define diffuse bidirectional reflectance as varying with angle of incidence and angle of reflection .
Absorptivity	Appears only when you select Absorptivity from the Specify Method list.Defines solar absorptivity. Absorptivity is required for all solar spectrum thermal radiation simulations.For more information, see Additional magnitude options.
Diffuse Bi-Directional Reflectance****Specify Field	Appears only when you select BRDF from the Specify Method list.Lets you specify the variation of diffuse bidirectional reflectance with angle of incidence (theta) and angle of reflection (phi).
Specular Reflectivity	Defines the magnitude of the surface's specular reflectivity. Solar specular reflectivity is required for modeling surfaces that are specular for solar spectrum radiation.For more information, see Additional magnitude options.
Transmissivity	Defines transmissivity as a constant value or that varies with direction of incidence (theta) and angle of incidence (phi).Note: When you specify different transmissivity values for top and bottom thermo-optical modeling objects, Thermal always uses the transmissivity value of the top side only.This is because the transmissivity is a property of the material, not a property of the surface, as for example, emissivity. For more information, see Additional magnitude options.
Non Gray Properties
Appears when Type is set to Non-Gray — Wavelength Dependent.
Emissivity	Defines emissivity as a constant value or as varying with wavelength. Emissivity is required for all thermal radiation simulations. For more information, see Additional magnitude options.
Specular Reflectivity	Defines specular reflectivity, which is required for modeling surfaces that are specular to the wavelengths you are simulating.You can define specular reflectivity as an expression as varying with the independent variable wavelength or as varying with two independent variables: the angle of incidence and direction of incidence.For more information, see Additional magnitude options.
Transmissivity	Defines transmissivity, which is required when your model needs to be transparent to the wavelengths you are simulating.You can define transmissivity as an expression as varying with the independent variable wavelength or as varying with two independent variables: the angle of incidence and direction of incidence.Note: When you specify different transmissivity values for top and bottom thermo-optical modeling objects, Thermal always uses the transmissivity value of the top side only. This because the transmissivity value in a mesh is calculated constant.For more information, see Additional magnitude options.
Index of Refraction
Index of Refraction	Specifies the index of refraction. Index of refraction is required for modeling refraction of radiation through transmissive surfaces.

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Define thermo-optical properties

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Thermo-optical properties

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Understanding bidirectional reflectance angles

Bidirectional reflectance distribution functions (BRDF)

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Thermo-Optical Properties - Advanced dialog box (Thermal/SST/ESC/Multiphysics), Simcenter 3D 2021.1 Series

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