Bidirectionally Coupled Ray Tracing Study Step
The Bidirectionally Coupled Ray Tracing study step is a dedicated study step for ray heating and similar applications.
It should only be used if all of the following criteria are met:
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If condition 4 is not satisfied, instead use a Stationary study step for the fields, followed by a Ray Tracing study step for the rays.
In addition to the settings that are available for the Ray Tracing study step, it is possible to specify a Number of iterations. The default value is 5. If the Bidirectionally Coupled Ray Tracing study step is used with The Ray Heating Interface, the following iterative solver loop is automatically set up to compute the ray trajectories and temperature:
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Alternate between Steps 2 and 3 for the specified Number of iterations, or specify a Global variable whose convergence will be used to terminate the loop.
The result of the iterative solver loop is that the heat source generated by the attenuation of rays is taken into account when computing the temperature. By including a thermo-optic dispersion model, such as the Temperature-dependent Sellmeier model, the temperature in turn affects the ray paths. Thus, a bidirectional coupling is established between the two physics interfaces.
Like any COMSOL Multiphysics simulation, it is possible to extend this bidirectional coupling to include other physical effects. For example, to include structural deformation due to thermal stress, add the Solid Mechanics physics interface and the Thermal Expansion Multiphysics coupling.
Thermally Induced Focal Shift in High-Power Laser Focusing Systems: Application Library path Ray_Optics_Module/Structural_Thermal_Optical_Performance_Analysis/thermally_induced_focal_shift
In the COMSOL Multiphysics Reference Manual: