## How to Generate Randomized Inhomogeneous Material Data

##### Bjorn Sjodin June 20, 2017

You can generate and visualize randomized material data with specified statistical properties determined by a spectral density distribution by using the tools available under the Results node in the COMSOL Multiphysics® software. In this blog post, we show examples that are quite general and have potential uses in many application areas, including heat transfer, structural mechanics, subsurface flow, and more.

### How to Create a Randomized Geometry Using Model Methods

##### 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.

### How to Generate Random Surfaces in COMSOL Multiphysics®

##### Bjorn Sjodin June 2, 2017

To easily generate random-looking geometric surfaces, the COMSOL Multiphysics® software provides a powerful set of built-in functions and operators, such as functions for uniform and Gaussian random distributions and a very useful sum operator. In this blog post, we show you how to generate a randomized surface with what amounts to a “one liner” expression with detailed control of the constituent spatial frequency components that determine the nature of the surface’s roughness.

### How to Add Stop Conditions to Solvers in COMSOL Multiphysics®

##### Temesgen Kindo May 17, 2017

Sometimes a simulation runs longer than needed, not giving us a way to monitor intermediate results or stop conditionally. This can leave us staring at the monitor, ready to pounce. In this blog post, we discuss how to automate this process in the COMSOL Multiphysics® software. This way, we can work on something else while the software checks the conditions after each step. We also have the option to see what happens the first time the conditions are violated.

### How to Inspect Your Mesh in COMSOL Multiphysics®

##### Hanna Gothäll May 12, 2017

Creating a suitable mesh for your FEA simulations is crucial for getting accurate results. In this blog post, we discuss how to check entities reported in mesh warnings and errors, how to view the statistics of a mesh or parts of a mesh, as well as how to plot the mesh and mesh-specific quantities and delimit these plots to selected regions.

### How to Manage Multiple Solutions in COMSOL Multiphysics®

##### Magnus Ringh May 10, 2017

If you’re looking for ways to manage multiple solutions, version 5.3 of the COMSOL Multiphysics® software offers several new tools for doing so. These include options for combining two solutions into one; storing solutions in different data sets so that they can be postprocessed and analyzed individually; and joining solutions to, for example, compare them. In this blog post, we will look at how to use these new tools.

### Exploiting Maximum Principles to Save Time and Resources

##### 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.

### How to Use the Find and Auto Completion Tools for Faster Model Setup

##### Amelia Halliday May 8, 2017

When making improvements to a model in the COMSOL Multiphysics® software, you are likely to add more parameters and variables. As the complexity of your model grows, it can become difficult to keep track of where these parameters are being used and defined, as well as to recall them for use in the settings of other nodes. In this blog post, we show you how to use the Auto Completion and Find tools for efficient model setup.

### How to Postprocess Fields over Arbitrary Geometries

##### 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.

### How to Compute Distances Between Objects in COMSOL Multiphysics®

##### 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.

### 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.