Wave Optics Module Updates

For users of the Wave Optics Module, COMSOL Multiphysics® version 6.2 introduces performance improvements to the Electromagnetic Waves, Boundary Elements interface, new impedance boundary conditions, and a tutorial model that describes wave propagation in liquid crystals. Learn more about these updates below.

Performance Improvements for the Electromagnetic Waves, Boundary Elements Interface

In the settings for the Electromagnetic Waves, Boundary Elements interface, it is now possible to select symmetry planes to reduce computation time. The symmetry settings also control the far-field calculations and the physics-controlled meshing. The new RCS of a Metallic Sphere Using the Boundary Element Method (RF) model showcases this functionality.

Furthermore, boundary element method (BEM) simulations on clusters are up to 2.5 times faster than in previous versions. If you also include the effect of reducing the model using a symmetry plane, then the simulation times are up to 4 times faster. Additionally, the load and memory balancing for BEM models running on clusters has been significantly improved.

An airplane model showing the bistatic radar cross section in the Thermal Wave color table.
Frontal-aspect, bistatic radar-cross-section (RCS) calculation using a half-size model supported by a perfect magnetic conductor (PMC) symmetry plane.

New and Improved Features in the Electromagnetic Waves, Boundary Elements Interface

The Impedance Boundary Condition and the Layered Impedance Boundary Condition have been added to the Electromagnetic Waves, Boundary Elements interface. These boundary conditions handle metallic exterior domains and metallic exterior domains covered by a layer structure, respectively. You can view this new addition in the Modeling of Dipole Antenna Array Using the Boundary Element Method tutorial model.

The default feature, Wave Equation, Electric, now includes all standard Electric displacement field model options, such as Relative permittivity, Refractive index, Dielectric loss, etc. This simplifies the use of different materials, supporting different material models.

The COMSOL Multiphysics UI showing the Model Builder with the Impedance Boundary Condition node highlighted, the corresponding Settings window, and a dipole antenna array model in the Graphics windows.
To characterize the metallic surfaces of a dipole antenna array with finite conductivity, the Impedance Boundary Condition is applied.

Wave Propagation Through Liquid Crystals

A new tutorial model demonstrates the switching capability of a liquid-crystal (LC) display cell in an in-plane switching (IPS) configuration. The Oseen–Frank model is used to solve for the LC director (optical axis) distribution when a static electric field is applied. An equation-based interface is used to define the Oseen–Frank equation, whereas the Electrostatics interface is used to solve for the electric potential distribution. For the given inhomogeneous anisotropic LC material, a full-wave simulation is performed using the Electromagnetic Waves, Frequency Domain interface.

A nematic liquid crystal model showing the electric potential distribution in the Thermal Wave color table and the electric field with a streamline plot in the Thermal color table.
The arrows show the nematic liquid crystal director (optical axis) distribution. The colors represent the electric potential distribution, and the streamlines represent the electric field.

Incident Wave Direction Input Field for Gaussian Beams

When using the Gaussian beam input option in the Scattering Boundary Condition and Matched Boundary Condition features in the Electromagnetic Waves, Beam Envelopes interface, there is a new Incident wave direction input field. This input field specifies the main propagation direction for the incident Gaussian beam, enabling greater flexibility when specifying Gaussian input beams with complex inhomogeneous wave-vector distributions on the interface node.

Electrical Conductivity Added to Drude–Lorentz and Debye Dispersion Models

The Drude–Lorentz and Debye dispersion models now have additional flexibility, allowing separate input of the electrical conductivity.

Higher-Order Elements

In this version, up to seventh-order curl elements can now be used in the Electromagnetic Waves, Frequency Domain interface and the Electromagnetic Waves, Transient interface.

Cyclic Symmetry for Periodic Condition

Cyclic symmetry has been added as a periodicity option for the Periodic Condition feature. This option provides the ability to perform simulations of one sector of a full, cyclically symmetric model as opposed to the full model, reducing computation time.

The COMSOL Multiphysics UI showing the Model Builder with the Periodic Condition node highlighted, the corresponding Settings window with the Cyclic symmetry periodicity option selected, and cyclically arranged electric dipoles in the Graphics window.
The electric field in the radial direction for cyclically arranged electric dipoles. The left plot shows the full solution, and the middle plot shows a full revolution of the simulation results for only one sector (the rightmost plot). A sector dataset was used in the middle plot to accomplish the data generation.

Time-Domain Physics-Controlled Mesh

The time-domain interfaces, Electromagnetic Waves, Transient and Electromagnetic Waves, Time Explicit, now provide physics-controlled mesh suggestions based on the frequency or wavelength content of a simulation. The following tutorial models showcase this new update:

The COMSOL Multiphysics UI showing the Model Builder with the Mesh node highlighted, the corresponding Settings window with the frequency mesh element size option selected, and a dual-band antenna model in the Graphics window.
The maximum mesh size is determined by the frequency of primary interest.

Hexagonal Uniform Array Factor

The hexagonal uniform array factor quickly estimates the far-field pattern of antenna arrays on a triangular grid. In version 6.2, the hexagonal antenna arrays provide lower sidelobes, more robust performance with better resolution, lower spatial noise, and wider coverage.

Two uniform hexagonal antenna models showing the far-field pattern in the Thermal Wave color table.
A 169-element antenna array can be estimated quickly by a periodic unit cell model combined with the new hexagonal uniform array factor.

Instantaneous Norm Variables for Vector Quantities

There are new variables that can be added to the form phys.normXi = sqrt(real(Xx)^2+real(Xy)^2+real(Xz)^2), where phys is a placeholder for any physics tag, such as ewfd, and X is a placeholder for a physical quantity, such as an electric field (E), magnetic field (H), etc. These variables are especially useful when visualizing time-harmonic vector waves.

The instantaneous norm of surface current density (left) on a curved metallic surface provides a more dynamic visualization of wave behavior compared to the conventional norm definition (right).

User-Defined Surface Impedance

In the Impedance Boundary Condition feature and the Layered Impedance Boundary Condition feature, it is now possible to directly enter a surface impedance. Previously, the surface impedance was calculated indirectly from the material properties defined on the boundary or in the feature settings. This simplifies the modeling process for problems where it is less relevant to use actual materials for modeling the exterior domain.

Optical Material Library Updates

Within the Optical material library, available in the Ray Optics Module and the Wave Optics Module, more than 90 new glasses from CDGM Glass Co., Ltd. have been added. The new glasses contain all of the necessary properties to perform structural-thermal-optical performance (STOP) analysis.

New Tutorial Models

COMSOL Multiphysics® version 6.2 brings the following new tutorial models to the Wave Optics Module.