## How to Perform Various Rotor Analyses in the COMSOL® Software

##### Prashant Srivastava July 12, 2017

Vibration in rotating machinery is very sensitive to the geometric, structural, and inertial properties of the various rotating and stationary components interacting with each other. These properties include the location of the mounted components and their inertial properties, bearing characteristics, and shaft properties. To understand the effects of these parameters, start with a simple model and perform various analyses to correlate the rotor response within the same model. Let’s demonstrate this process with a simply supported beam rotor example.

### How to Export Images Automatically After Solving Your Model

##### Bjorn Sjodin July 11, 2017

In a previous blog post, we looked at setting up a programmatic sequence of operations under the Study node for solving, saving a model to file, and exporting data to file. Today, we are building on this knowledge to show how an entire sequence of images can be automatically exported after solving a model in the COMSOL Multiphysics® software.

### Analyzing a Probe Tube Microphone Design with Acoustics Simulation

##### Bridget Cunningham July 10, 2017

Of the 72 million potential hearing aid users around the world, each needs a device fitted to meet their needs. In-the-ear measurements are performed to ensure both comfort and effectiveness. These measurements require the use of a microphone — the size of which can cause issues. The device can be too large to fit into the measured sound field. Alternatively, it can be too big compared to the wavelength and disturb the acoustic field. One solution is a probe tube…

### 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.

### Introduction to Plasma Modeling with Non-Maxwellian EEDFs

##### Annette Pahl July 5, 2017

Plasma modeling normally requires knowing the electron energy distribution function (EEDF) as well as transport properties like electron mobility and diffusivity. To accurately calculate these quantities with the Boltzmann equation, we must also know the electron density (and possibly the density of all species subject to electron impact reactions). However, the electron (and species densities) are outputs of a plasma model, resulting in a catch-22. Let’s take a look at how to overcome this challenge using an example app.

### Analyzing Laser Beam-Matter Interaction in Selective Laser Melting

##### Bridget Cunningham July 4, 2017

Many manufacturing processes already benefit from selective laser melting. The potential for combining this technique with high-melting materials is clear, but there are challenges to consider. For instance, these materials have a much narrower processing window. To better understand their behavior in selective laser melting, one research group built a model to analyze the thermal and fluid dynamics of laser beam-matter interaction. Their results generated further momentum in extending the use of this technique to process refractory metals.

### How to Import an ECAD Geometry for Printed Circuit Board Design

##### Lorant Olasz July 3, 2017

Have you ever wondered how to import the geometry of a printed circuit board (PCB) into the COMSOL Multiphysics® software and prepare it for meshing and analysis? Version 5.3 of the COMSOL® software has the tools to generate geometric objects from the 2D layouts of ECAD files, group them into easy-to-use selections for simulation setup, and automatically take care of the geometric complexity inherent to ECAD formats before meshing. We also have a new tutorial model to demonstrate this functionality.

### Creating a Model Geometry in COMSOL Multiphysics®

##### Amelia Halliday June 29, 2017

Creating the geometry for your model is one of the first steps of setting up a simulation. In the COMSOL Multiphysics® software, there are many geometry operations, tools, and functionality that enable you to do this. These include geometric primitives; Boolean, partition, and transformation operations; work plane operations; and other CAD tools. Here, we highlight all of this functionality and, near the end, link to a video tutorial series that shows how to use them while building your model geometry.

### How to Automate Physics Choices and Studies Using Model Methods

##### 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.

### Designing a Butler Matrix Beamforming Network with RF Modeling

##### Caty Fairclough June 27, 2017

When looking for a cost-effective feed network, engineers can turn to the Butler matrix as a potential solution. This passive beamforming feed network is used with phased array antennas, which have applications in upcoming technologies like 5G. To efficiently analyze and design Butler matrix feed networks, we can turn to the COMSOL Multiphysics® software and the add-on RF Module.

### Why Should I Use Automatic Wall Treatment for My CFD Modeling?

##### Ed Fontes June 26, 2017

Wall-bounded turbulent flows display extreme gradient close to the walls. The most accurate way to treat these gradients is to resolve them using a low Reynolds number model, which is computationally expensive. Industrial applications use wall functions, which model the flow closest to the wall rather than resolving it. Wall functions are robust and efficient, but not particularly accurate. New automatic wall treatment functionality in the COMSOL® software combines the benefits of wall functions and the low Reynolds number model.