## How to Implement the Fourier Transformation from Computed Solutions

##### Yosuke Mizuyama | February 27, 2017

We previously learned how to calculate the Fourier transform of a rectangular aperture in a Fraunhofer diffraction model in the COMSOL Multiphysics® software. In that example, the aperture was given as an analytical function. The procedure is a bit different if the source data for the Fourier transformation is a computed solution. In this blog post, we will learn how to implement the Fourier transformation for computed solutions with an electromagnetic simulation of a Fresnel lens.

Read More##### Caty Fairclough | February 21, 2017

The COMSOL Multiphysics® software includes many built-in physics equations and interfaces, but there may be times when you need to implement physics that aren’t part of the software to solve your modeling problem. You can use the flexibility of the COMSOL® software to add user-defined equations via equation-based modeling. Today, we discuss using equation-based modeling to solve a shallow water equation, which can be used to analyze coastal erosion.

Read More##### Andrew Griesmer | February 7, 2017

The Open Recovery File feature is a somewhat unknown feature in the COMSOL Multiphysics® software, but it’s useful for anyone running simulations that give multiple solutions. If, for any reason, the software shuts down before the simulation finishes, you can open a recovery file so that you don’t lose your work. Here, we highlight a tutorial video on how to open these files to recover “lost” work as well as go over the strengths and limitations of this feature.

Read More##### Hanna Gothäll | February 1, 2017

Topology optimization can be a useful step in your design process, but the generated designs often require further analysis. With the COMSOL Multiphysics® software, you can create geometries out of your topology optimization result plots and easily export them to CAD software. In this blog post, we discuss how to do so, using both 2D and 3D examples.

Read More##### Amelia Halliday | January 10, 2017

The COMSOL Multiphysics® software helps you find solutions to your engineering questions, but you may also have questions on using the simulation software itself. Therefore, we’ve created resources to guide your modeling process. In this blog post, we discuss three help tools that you can access in COMSOL Multiphysics: the Help window, Documentation window, and Application Library. We also link to a video that shows you how to access and use these tools at the end of this post.

Read More##### 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.

Read More##### Andrew Griesmer | December 8, 2016

If you’ve read the COMSOL Blog before, you might know that we like to include animations in our blog posts to help illustrate concepts more clearly. Most of these animations are exported directly from the COMSOL Multiphysics® software, which means that you can export animations for your own simulations, too. At the bottom of this post, we link to a video to show you how to do that.

Read More##### 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.

Read More##### 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.

Read More##### Amlan Barua | November 10, 2016

In a previous blog post, we discussed the physiological basis of generating action potential in the excitable cells of living organisms. We spoke about the simple Fitzhugh-Nagumo model, which emulates the process of depolarization and repolarization in a cell’s membrane potential. Today, we analyze a more advanced model for simulating action potential, the Hodgkin-Huxley model. We also go over how to use a computational app to streamline this type of analysis.

Read More##### Amlan Barua | October 7, 2016

In 1961, R. Fitzhugh (Ref. 1) and J. Nagumo proposed a model for emulating the current signal observed in a living organism’s excitable cells. This became known as the FitzHugh-Nagumo (FN) model of mathematical neuroscience and is a simpler version of the Hodgkin-Huxley (HH) model (Ref. 2), which demonstrates the spiking currents in neurons. In today’s blog post, we’ll examine the dynamics of the FN model by building an interactive app in the COMSOL Multiphysics® software.

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