## Modeling Natural and Forced Convection in COMSOL Multiphysics®

##### Walter Frei April 28, 2017

Whenever we have a heated or cooled part exposed to air, there is some transfer of heat from the part to the air via convection. The movement of the air can be either forced, via a fan, or free, as a result of the natural buoyancy variations due to changes in the air temperature. Today, we will look at several different ways of modeling these types of convection in the COMSOL Multiphysics® software.

Read More##### Walter Frei April 20, 2017

When designing electromagnetic coils, we may want to adjust the position of the coils to achieve a desired magnetic field strength within a particular region of space. This is possible to do within the COMSOL Multiphysics® software by using the add-on AC/DC Module and Optimization Module to combine parameter and shape optimization. Let’s find out how.

Read More##### Walter Frei April 10, 2017

If you design electromagnetic coils, the combination of the AC/DC and Optimization modules with the COMSOL Multiphysics® software gives you the power to quickly come up with improved design iterations. Today, we will look at designing a coil system to achieve a desired magnetic field distribution by changing the coil’s driving currents. We will also introduce three different optimization objectives and constraints. This topic is of interest to anyone who is modeling coils or curious about optimization.

Read More##### Walter Frei April 4, 2017

Have you ever wanted to query the results of your model within an arbitrary geometric subregion? You might think that this requires adding geometries to a model and recomputing the solution. Instead, in the COMSOL Multiphysics® software, we can just add and reposition a part solely for the purpose of evaluating the results. We will demonstrate this in the context of computing mutual inductance between coils and discuss simpler techniques that can be used for a reduced set of cases.

Read More##### Walter Frei March 2, 2017

Have you ever modeled deforming objects in the COMSOL Multiphysics® software and wanted to know the distance between them? In today’s blog post, we will look at how to compute distances between objects using methods for determining the closest distance field. We’ll also find out how to use the distance field as a part of a multiphysics model.

Read More##### Walter Frei February 14, 2017

Overhead power cables can be seen almost everywhere in the United States, but there are also many underground power cables that we can’t see. They have the advantage of protection from wind and snow damage and, due to their shielding, have greatly reduced electromagnetic field emission. One disadvantage of underground cables is that they heat up significantly, which leads to degradation of the insulation and failure. Let’s see how to model electromagnetic heating in the COMSOL Multiphysics® software.

Read More##### Walter Frei August 11, 2016

Extending our discussion on modeling the harmonic excitations of linear systems, we will now shift focus to nonlinear systems. We will look at problems where the loading on the system has some sinusoidal components as well as cases where the material properties or loads and constraints depend directly on the solution. As you will see, COMSOL Multiphysics can address these apparently nonlinear cases with some very efficient solution algorithms. Let’s find out how.

Read More##### Walter Frei August 10, 2016

In many engineering situations, we can assume that excitations on the system of interest and the responses are sinusoidal over time. When this assumption holds, we can use a so-called frequency-domain analysis, which leads to some very efficient solution techniques. Let’s go over a few basic concepts and the conditions under which we can make this assumption, while exploring various solution approaches to take.

Read More##### Walter Frei June 30, 2016

Thermostats are used in most homes for controlling furnaces and air conditioners to maintain a comfortable interior temperature. A simple thermostat controlling a heater will have on and off setpoints. Such a control scheme is easy to implement within COMSOL Multiphysics using the Events interface, as presented in a previous blog post. Today, we will expand this technique to include a delay, a time lag between turning the heater on or off, in a thermostat simulation.

Read More##### Walter Frei June 22, 2016

Have you ever wanted to quickly predict the temperature of an enclosed structure, such as your house, that is exposed to ambient environmental conditions? The temperature inside depends on the surrounding air temperature, wind speed, and solar loads, all of which have significant variability. For simplicity, we often also want to approximate the inside air as well-mixed. Today, we will discuss the tools in COMSOL Multiphysics that help you quickly build such thermal models.

Read More##### Walter Frei April 6, 2016

Have you ever wanted to write out mesh and analysis data from COMSOL Multiphysics into a text file? You may want to do this when passing information to another software program or even just into a spreadsheet. You often want to customize the exact format in which such data is written, depending upon the needs of the other tools with which you are working. This is very easy to do with the Application Builder. Let’s find out how!

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