The Ray Heating Interface
The Ray Heating interface () combines the Geometrical Optics interface with the Heat Transfer in Solids interface. The Ray Heat Source multiphysics feature is added automatically. The Ray Heating interface is used to model electromagnetic wave propagation in optically large systems in which the refractive index is temperature dependent. The energy lost due to the attenuation of rays in an absorbing medium creates a heat source that is included in the temperature computation.
When a predefined Ray Heating interface is added from the Optics>Ray Optics branch () of the Model Wizard or Add Physics windows, Geometrical Optics and Heat Transfer in Solids interfaces are added to the Model Builder. A Multiphysics node is also added, which automatically includes the multiphysics coupling feature Ray Heat Source.
On the Constituent Physics Interfaces
The Geometrical Optics interface is used to model electromagnetic wave propagation when the wavelength is much smaller than the smallest geometric entity in the model. It includes built-in tools for computing the intensity, phase, and optical path length of rays. The rays can be polarized, unpolarized, or partially polarized. Frequency distributions and ray propagation in absorbing media are also supported.
The Heat Transfer in Solids interface is used to model heat transfer by conduction, convection, and radiation. A Heat Transfer in Solids model is active by default on all domains and a Heat Transfer in Fluids model is added with an empty selection. All functionality for including other domain types, such as a fluid domain, is also available. The temperature equation defined in solid domains corresponds to the differential form of the Fourier’s law that may contain additional contributions like heat sources.
Settings for Physics Interfaces and Coupling Features
When physics interfaces are added using the predefined couplings, for example Ray Heating, specific settings are included with the physics interfaces and the coupling features.
However, if physics interfaces are added one at a time, followed by the coupling features, these modified settings are not automatically included.
For example, if single Geometrical Optics and Heat Transfer in Solids interfaces are added, COMSOL adds an empty Multiphysics node. You can choose from the available coupling features but the modified settings are not included.
Coupling features are available from the context menu (right-click the Multiphysics node) or from the Physics toolbar, Multiphysics menu.
Table 4-1: Modified Settings for a Ray Heating Interface
Physics Interface or Coupling Feature
Modified Settings (if any)
Geometrical Optics
Compute intensity and power is selected from the Intensity computation list in the physics interface Ray Properties section.
Heat Transfer in Solids
No changes.
Ray Heat Source
The Domain Selection is the same as that of the participating physics interfaces.
The corresponding Geometrical Optics and Heat Transfer in Solids interfaces are preselected in the Ray Heat Source section.
Physics Interfaces and Coupling Features
Use the online help in COMSOL Multiphysics to locate and search all the documentation. All these links also work directly in COMSOL Multiphysics when using the Help system.
Coupling Features
The Ray Heat Source coupling feature node is described in this section.
Physics Interface Features
Physics nodes are available from the Physics ribbon toolbar (Windows users), Physics context menu (Mac or Linux users), or right-click to access the context menu (all users).
In general, to add a node, go to the Physics toolbar, no matter what operating system you are using. Subnodes are available by clicking the parent node and selecting it from the Attributes menu.
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The available physics features for The Geometrical Optics Interface are listed in the section List of Geometrical Optics Interface Physics Features.
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The available physics features for The Heat Transfer Interfaces are listed in the sections Domain Features, Boundary Features, and Edge and Point Features in the COMSOL Multiphysics Reference Manual.