## Which Turbulence Model Should I Choose for My CFD Application?

##### Walter Frei July 6, 2017

The COMSOL Multiphysics® software offers several different formulations for solving turbulent flow problems: the L-VEL, algebraic yPlus, Spalart-Allmaras, k-ε, k-ω, low Reynolds number k-ε, SST, and v2-f turbulence models. These formulations are available in the CFD Module, and the L-VEL, algebraic yPlus, k-ε, and low Reynolds number k-ε models are also available in the Heat Transfer Module. In this blog post, learn why to use these various turbulence models, how to choose between them, and how to use them efficiently.

Read More##### Walter Frei June 22, 2017

Do you ever find yourself performing the same modeling operations over and over again in each new model file that you work with? Or do you work with colleagues who send you model files that you have to manually add physics and features to? If so, you can greatly accelerate your workflow by using model methods, new in version 5.3 of the COMSOL Multiphysics® software. Let’s find out how.

Read More##### Walter Frei June 6, 2017

Whenever light is incident on a dielectric material, like glass, part of the light is transmitted while another part is reflected. Sometimes, we add a metal coating, such as gold, which alters the transmittance and reflectance as well as leads to some absorption of light. The dielectric surface and the metal coating also often have some random variations in height and thickness. In this blog post, we will introduce and develop a computational model for this situation.

Read More##### Walter Frei June 5, 2017

Have you ever wanted to include a randomly created geometry in your model? Perhaps you want to simulate a natural material or an arrangement of parts that has some known statistical distribution of dimensional variations. In such cases, we may want to create a random geometry in the COMSOL Multiphysics® software. With the release of version 5.3, we can now create random geometries using a model method. Let’s take a look at how to do so with a tasty example.

Read More##### 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.

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