All posts by Walter Frei

Walter Frei | May 27, 2015

Whenever we are solving a wave electromagnetics problem in COMSOL Multiphysics, we build a model that is composed of domains and boundary conditions. Within the domains, we use various material models to represent a wide range of substances. However, from a mathematical point of view, all of these different materials end up being handled identically within the governing equation. Let’s take a look at these various material models and discuss when to use them.

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Walter Frei | May 14, 2015

Metals are materials that are highly conductive and reflect an incident electromagnetic wave — light, microwaves, and radio waves — very well. When using the RF Module or the Wave Optics Module to simulate electromagnetics problems in the frequency domain, there are several options for modeling metallic objects. Here, we will look at the Impedance and Transition boundary conditions as well as the Perfect Electric Conductor boundary condition, offering guidance on when to use each one.

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Walter Frei | April 14, 2015

There are several different add-on modules to the COMSOL Multiphysics® software for working with external CAD and ECAD data. These modules allow both unidirectional and bidirectional data transfer between the COMSOL Multiphysics analysis tools and the CAD and ECAD software that you are using for design. In this blog post, we will cover the functionality of these various modules and describe why you may want to use them.

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Walter Frei | April 13, 2015

High-intensity lasers incident upon a material that is partially transparent will deposit power into the material itself. If the absorption of the incident light can be described by the Beer-Lambert law, it is possible to model this power deposition using the core functionality of COMSOL Multiphysics. We will demonstrate how to model the absorption of the laser light and the resultant heating for a material with temperature-dependent absorptivity.

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Walter Frei | March 27, 2015

Often, the most tedious step of finite element modeling is subdividing your CAD geometry into a finite element mesh. This step, usually just called meshing, can sometimes be fully automated. More often, however, the careful finite element analyst will want to semi-manually create their meshes. Although this does require more work, sometimes there are significant advantages in doing so. In this blog entry, we will look at one of the key manual meshing techniques: the concept of geometric partitioning.

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Walter Frei | March 19, 2015

We often need to work with experimental data in COMSOL Multiphysics, usually to represent material properties or other inputs to our model. However, experimental data is often noisy; it contains experimental errors that we do not want to introduce into our simulations. In this blog post, we will look at how to fit smooth curves and surfaces to experimental data using the core functionality of COMSOL Multiphysics.

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Walter Frei | March 9, 2015

When using the COMSOL Multiphysics software to simulate wave electromagnetics problems in the frequency domain, there are several options for modeling boundaries through which a propagating electromagnetic wave will pass without reflection. Here, we will look at the Lumped Port boundary condition available in the RF Module and the Port boundary condition, which is available in both the RF Module and the Wave Optics Module.

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Walter Frei | February 19, 2015

A thermostat is a device that senses the temperature of a system and uses this information to control the system’s heaters, or coolers, to keep the temperature close to a desired setpoint. While there are many different types of thermostats, we will focus today on one that turns a heater either on or off based upon two setpoints. This is known as an on-off or a bang-bang controller, and it can be implemented with the Events interface in COMSOL Multiphysics.

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Walter Frei | February 16, 2015

One of the more common questions we are asked is about the modeling of periodic, or pulsed, heat loads. That is, a heat load that turns on and off repeatedly at known times. Modeling such a situation accurately and efficiently in COMSOL Multiphysics is quite easy to do with the Events interface. The techniques we will introduce are applicable to many classes of time-dependent simulations in which you have changes in loads that occur at known times.

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Walter Frei | January 28, 2015

When solving wave electromagnetics problems, it is likely that you will want to model a domain with open boundaries — that is, a boundary of the computational domain through which an electromagnetic wave will pass without any reflection. COMSOL Multiphysics offers several solutions for this. Today, we will look at using scattering boundary conditions and perfectly matched layers for truncating domains and discuss their relative merits.

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Walter Frei | January 14, 2015

One of the common modeling situations that we encounter is the simulation of rotating objects exposed to loads. There are many ways in which such rotation can be modeled. In this blog post, we will look at addressing this by using the General Extrusion operators and discuss why this approach is useful.

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