## How to Model Conductors in Time-Varying Magnetic Fields

##### Walter Frei May 25, 2018

One of the more common uses of the AC/DC Module, an add-on to the COMSOL Multiphysics® software, is for modeling conductors and other lossy materials in time-varying magnetic fields when there are significant induced currents. The appropriate modeling approach depends upon how quickly the magnetic fields vary over time. Here, we review the basics and describe various modeling techniques to use.

### Analyzing Magnetotellurics with Electromagnetics Simulation

##### Caty Fairclough May 17, 2018

Mount Erebus, one of Earth’s most remote volcanoes, sits covered in snow and ice. These chilly surroundings can be misleading, as Mount Erebus has another claim to fame: It’s the most active volcano in Antarctica. One option for mapping its magma flow is with a technique called magnetotellurics (MT), which measures the electrical resistivity of Earth’s crust. To study and improve MT, engineers can analyze its performance with electromagnetics simulation.

### Common Pitfalls in Electrothermal Analysis

##### Walter Frei April 17, 2018

In applications such as power transfer and consumer electronics, it may be critical to model electromagnetic heating of materials that are nonlinear in temperature; that is, the material’s electrical conductivity and thermal conductivity vary with temperature. When modeling these nonlinearities, even an experienced analyst can sometimes get quite unexpected results due to the combination of the nonlinear material properties, boundary conditions, and geometry. Let’s find out why this is in terms of a very simple example.

### Redesigning Faraday’s Wheel: Creating Efficient Homopolar Generators

##### Bridget Paulus April 9, 2018

Acyclic generator, unipolar generator, disc dynamo, Faraday wheel — No matter what you call it, the homopolar generator is an interesting device. Unlike most generators, homopolar generators produce high current with low voltage and can store and release large amounts of electricity. Due to these abilities, scientists have worked to improve this device since its invention. To continue this work, you can evaluate the performance of homopolar generator designs using the COMSOL Multiphysics® software.

### Topology Optimization of a Magnetic Circuit for Loudspeakers

##### Thomas Forrister March 22, 2018

In the 1970s and 80s, music fans would dedicate entire rooms of their homes to stereo systems. Big, boxy loudspeakers were essential fixtures of these stereo setups. Today, a new trend has emerged: Consumers want loudspeakers that are both powerful and portable, with the ability to connect to devices around the house and on the go. To design sophisticated yet lightweight loudspeakers, you can optimize the topology of their components, such as a magnetic circuit for the loudspeaker driver.

### Modeling Ferromagnetic Materials in COMSOL Multiphysics®

##### Cesare Tozzo January 23, 2018

Ferromagnetic materials are ubiquitous in electronic components and electrical machinery. In EM modeling, we may be interested in the broader application or focus on a certain material characteristic (e.g., the mechanical resistance of structural steel) that happens to be magnetic. In both cases, ferromagnetic parts influence the magnetic field in their surroundings, and identifying exactly how this happens could be crucial to the proper functioning of a device or system.

### Model Deforming Objects with the Arbitrary Lagrangian-Eulerian Method

##### Edmund Dickinson January 17, 2018

As two of the greatest mathematicians to have ever lived, Leonhard Euler and Joseph-Louis Lagrange made numerous contributions to continuum mechanics. Combining their individual descriptions of the subject inspired the arbitrary Lagrangian-Eulerian (ALE) method, a technique that can be used for a multitude of simulation applications. Find out how the work of Euler and Lagrange helped create the ALE method and how it aids your simulations in the COMSOL Multiphysics® software.

### Modeling Cables in COMSOL Multiphysics®: 6-Part Tutorial Series

##### Brianne Costa December 29, 2017

Want a roadmap to modeling cables? We have a six-part tutorial series for you. The Cable Tutorial Series shows how to model an industrial-scale cable in the COMSOL Multiphysics® software and add-on AC/DC Module, and also serves as an introduction to modeling electromagnetic phenomena in general. The numerical model is based on standard cable designs and validated by reported figures. Keep reading for a sneak peek of what you’ll learn when you roll up your sleeves and start the series.

### Analyzing an Electrodynamic Ion Funnel with COMSOL Multiphysics®

##### Caty Fairclough December 8, 2017

Within mass spectrometers, plasmas are often used to ionize a sample and an inert background gas. Before the ions produced in the plasma are sent into the mass filter, which determines the sample’s chemical composition, they must be focused into a beam with a suitably small radius. One way to focus ions is with an ion funnel. Focusing ions is a critical stage of the overall design, so it’s important to have a fundamental understanding of the funnel’s operating principles.

### Should I Fillet the Geometry in My Electromagnetic Heating Analysis?

##### Walter Frei November 30, 2017

To fillet or not to fillet, that is the question (that can bedevil the multiphysics analyst). When building finite element models, sharp edges can lead to local singularities and fields that are nonconvergent with mesh refinement. Rounding off these sharp edges by adding a fillet avoids this singularity. As it turns out, in many multiphysics models, these sharp edges and the resultant singularities do not necessarily negatively affect the results. Let’s find out more.

### Analyzing Magnetic Flow Meters for Blood Flow Measurement

##### Brianne Costa November 24, 2017

Magnetic flow meters are a noninvasive option for measuring blood flow. However, when patients move, displaced blood vessels can affect the sensitivity of the flow meter. Researchers from ABB Corporate Research used multiphysics modeling to study how the displacement of blood vessels in a moving patient impacts the performance of a magnetic flow meter.