## Defining a Multiphysics Model, Part 1: The Automatic Approach

##### Amelia Halliday November 6, 2018

To help understand the complicated universe we live in, we have compartmentalized physics phenomena into distinct disciplinary specializations. However, natural and engineering problems often cross these utilitarian borders. A major strength of the COMSOL Multiphysics® software is the ease with which such cross-disciplinary interactions, which we refer to as multiphysics interactions, can be accounted for. The COMSOL® software provides a plethora of built-in multiphysics couplings and even enables users to implement their own physics couplings.

Lire la Suite##### Pär Persson Mattsson June 12, 2018

In a previous blog post, we explained how to run a job from the COMSOL Multiphysics® software on clusters directly from the COMSOL Desktop® environment, without any interaction with a Linux® operating system terminal. Since this terminal is sometimes treated with excessive respect, the ability to start a cluster job directly from the graphical user interface is one of the most useful features in the COMSOL® software. Plus, there’s more to it… Enter the Cluster Sweep node.

Lire la Suite##### Temesgen Kindo June 28, 2017

You solved a model under certain assumptions. When you analyze the results, you find out that those assumptions do not hold. Now, you have to amend your analysis by incorporating new physics features or changing the study type. What if you could automate such processes? Today, we will discuss how to do so easily using the Model Method feature introduced in version 5.3 of the COMSOL Multiphysics® software.

Lire la Suite##### Temesgen Kindo May 9, 2017

When your simulations consume significant memory, do you buy a bigger computer? When they take too long to solve, do you just run them overnight? Often, you don’t have another option. But sometimes, if you have the right tools, you can find a better approach by exploiting the mathematical structure. Today, we will show you how to use the so-called maximum principles to save computational resources and time in the COMSOL Multiphysics® software.

Lire la Suite##### Jeff Hiller December 20, 2016

Do you find yourself creating new models in the COMSOL Multiphysics® software faster than you can launch them interactively in the COMSOL Desktop® environment? If having to wait for your current model to finish solving before launching the next one does not sound appealing, it’s time to learn how to run your simulations in Batch mode from the command line. As it turns out, this is quite a simple process.

Lire la Suite##### Jan-Philipp Weiss November 25, 2016

In a recent blog post, we discussed how to use the Domain Decomposition solver for computing large problems in the COMSOL Multiphysics® software and parallelizing computations on clusters. We show how to save memory by a spatial decomposition of the degrees of freedom on clusters and single-node computers with the Recompute and clear option. To further illustrate the Domain Decomposition solver and highlight reduced memory usage, let’s look at a thermoviscous acoustics problem: simulating the transfer impedance of a perforate.

Lire la Suite##### Jan-Philipp Weiss November 23, 2016

The Domain Decomposition solver is a memory-efficient iterative algorithm with inherent parallelism on the geometric level. We can use this method to compute large modeling problems that can’t be solved with other direct or iterative methods. This solver’s primary field of application is on clusters, but it can also enable the solution of large problems on laptops and workstations. Let’s see how to use this functionality in the COMSOL Multiphysics® software.

Lire la Suite##### Magnus Ringh September 2, 2016

A COMSOL Multiphysics® simulation typically includes one or more field quantities in its output. Depending on the number of field quantities, the geometry’s complexity, and the mesh density required for valid results, simulations can include millions of degrees of freedom (DOFs). Oftentimes, storing one or more scalar quantities or the results on a small geometry part is sufficient. Here, we explore tools for storing selected output quantities and minimizing model file sizes and the time required to display this data.

Lire la Suite##### Magnus Ringh April 27, 2016

You can use the residual operator, new with COMSOL Multiphysics version 5.2, to evaluate and plot your model’s algebraic residual in order to troubleshoot convergence issues. This blog post demonstrates the use of the residual operator for visualizing and understanding the convergence properties of a turbulent flow simulation.

Lire la Suite##### Bjorn Sjodin February 2, 2016

Have you ever run a large parametric sweep overnight, only to discover the next morning that the parametric solver is still not finished? You may wish you could inspect the solutions for the parameters that are already computed while waiting for the last few parameters to converge. The remedy to this problem is to use a batch sweep, which automatically saves the parametric solutions that were already computed on a file that you can open for visualization and postprocessing purposes.

Lire la Suite##### Walter Frei June 30, 2015

Over the last several weeks, we’ve published a series of blog posts addressing the various domain and boundary conditions available for wave electromagnetics simulation in the frequency domain; as well as modeling, meshing, and solving options. In this blog post, I will tie all of this information together and provide an introduction to the various types of problems that you can solve in the RF and Wave Optics modules.

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