COMSOL Multiphysics^® 6.1 Release Highlights

Ray Optics Module Updates

For users of the Ray Optics Module, COMSOL Multiphysics^® version 6.1 provides a new feature for computing fluence rates, improved pseudorandom number generation (PRNG), and additional materials in the Optical material library. Read about these updates and more below.

Fluence Rate Calculation

Fluence rate is defined as the amount of radiation that would hit a small spherical detector at any location in the simulation domain, divided by the cross-sectional area of such a detector. A new domain accumulator feature, Fluence Rate Calculation, is now available for computing fluence rate. This feature is valuable when simulating ultraviolet (UV) purification systems because it can be used to predict the amount of UV radiation that bacteria and other pathogens will absorb when passing by a source of UV radiation.

You can see this new feature in the new Annular Ultraviolet Reactor and Annular Ultraviolet Reactor with Particle Tracing tutorial models.

Slice plot of the fluence rate surrounding a UV lamp. A small fraction of rays is also shown.

Improved Pseudorandom Number Generation

The Ray Optics Module includes a variety of functionality that relies on PRNG, such as:

• Monte Carlo modeling of light extinction in particle-laden media
• Diffuse and isotropic scattering
• Surface normal perturbations for modeling rough boundaries
• Conditional ray–boundary interactions

The PRNG methods used in these examples have been improved and are less likely to incur correlations between random numbers that should ideally be uncorrelated. This includes random boundary conditions acting on different rays as well as unwanted correlations between randomly generated vector components. The existing Solar Dish Receiver tutorial model demonstrates this new improvement.

Reflected rays from a parabolic dish, including the effects of solar limb darkening and surface roughness. The roughness model applies a pseudorandomly generated perturbation to the surface normal direction when initializing the direction of each released ray.

Option to Store Only Accumulated Variables in Solution

Depending on your application, the accumulated variables (such as the deposited ray power or fluence rate within a domain) may be more valuable information than the position and direction of individual rays. You now have the option to retain only the accumulated variables in the solution while discarding the degrees of freedom associated with the rays, which reduces file size. You can see this feature in the new Annular Ultraviolet Reactor and Annular Ultraviolet Reactor with Particle Tracing tutorial models.

Settings for the Geometrical Optics interface when only the fluence rate is stored in the solution (not the individual ray positions) to reduce file size.

Optical Material Library Updates

In the Optical material library, available in the Ray Optics Module and Wave Optics Module, the fused silica and i-line glasses from Ohara Corporation have been added. Compared to other types of glass, fused silica and i-line glasses generally have greater transmittance at ultraviolet and near-UV wavelengths.

New Tutorial Models

COMSOL Multiphysics^® version 6.1 brings three new tutorial models to the Ray Optics Module.

Annular Ultraviolet Reactor

An ultraviolet (UV) water purification reactor. The slice plot is colored by the fluence rate in the water surrounding the UV lamp.

Application Library Title:
annular_ultraviolet_reactor
Download from the Application Gallery

Annular Ultraviolet Reactor with Particle Tracing

An ultraviolet (UV) water purification reactor with particle tracing. Particle trajectories through the UV reactor are colored by their accumulated dose. The slice plot shows the fluence rate in the water.

Application Library Title:
annular_ultraviolet_reactor_particle
Download from the Application Gallery

Ray Optics Modeling of a Fresnel Lens

Comparison of ray collimation in a Fresnel lens (left) and plano-convex lens (right).

Application Library Title:
ray_optics_modeling_fresnel_lens
Download from the Application Gallery