## How to Model Fluid-Structure Interaction in a Water Balloon

##### Phillip Oberdorfer December 15, 2017

The physics behind filling a water balloon seem simple at first glance, but involve a rather complex interplay of fluid flow and a nonlinear hyperelastic material. Fortunately, it is easy to set up and solve this type of model in the COMSOL MultiphysicsÂ® software. Let’s see how…

### Analyzing Magnetic Flow Meters for Blood Flow Measurement

##### Brianne Costa November 24, 2017

Magnetic flow meters are a noninvasive option for measuring blood flow. However, when patients move, displaced blood vessels can affect the sensitivity of the flow meter. Researchers from ABB Corporate Research used multiphysics modeling to study how the displacement of blood vessels in a moving patient impacts the performance of a magnetic flow meter.

### How to Use Dispersion Curves to Analyze Fluid-Filled Pipes

##### Ajit Bhuddi November 8, 2017

Suppose you have a very long system with a constant cross section: a fluid-filled pipe. Modeling this system is computationally expensive and time consuming. Using a guided wave propagation approach, you can model a cross section of the system and compute the guided waves along it. You can represent such waves by means of dispersion curves. Here, we discuss a coupled analysis considering air and water as the internal fluids. We also analyze the system dynamics using dispersion curves.

### Have You Heard About the Cocktail Party Problem?

##### Caty Fairclough November 7, 2017

From cocktail parties to public transit, there are competing sound sources in many everyday environments. If you want to listen to one specific sound, say a friend’s question, in a complex auditory setting, you have to distinguish between the sounds around you and focus on the one of interest. This situation is known as “the cocktail party problem”. Understanding how humans solve this problem can lead to advancements in hearing aid designs.

### Keynote Video: Modeling the Multiphysics Behavior of Nuclear Fuel

##### Bridget Paulus November 6, 2017

Optimizing fuel for nuclear reactors can increase the amount of power they generate, improve their safety, and lower greenhouse gas emissions. However, studying nuclear fuel can be complex, as it involves interactions between multiple physical phenomena. In his keynote talk from the COMSOL Conference 2017 Boston, Andrew Prudil of Canadian Nuclear Laboratories (CNL) discussed using multiphysics models to gain insight into nuclear fuel. If you missed his presentation, find a video recording and summary below.

### How to Implement Elastoplasticity in a Model Using External Materials

##### Mats Danielsson November 2, 2017

In structural mechanics, there may be situations when you want to implement your own material model. The COMSOL MultiphysicsÂ® software gives you the option to program your own material model in C code. The compiled code can then be called from the program using the External Material feature. Here, we demonstrate how to implement an external material model and then use it in an example analysis.

### Keynote Video: Using Simulation to Develop Reliable Audio Transducers

##### Caty Fairclough November 1, 2017

You’re listening to music when you bump into your loudspeaker, knocking it off the table. Fortunately, it still works! In his keynote presentation at the COMSOL Conference 2017 Boston, Richard Little discussed how Sonos, Inc. ensures that loudspeakers are durable enough to withstand certain stresses and how they use simulation to improve the robustness of the transducer component. If you missed his talk, you can watch the video recording below, followed by a quick summary of his presentation.

### Is That a Ghost? Vibroacoustic Explanations for False Poltergeists

##### Brianne Costa October 31, 2017

My favorite novel to read around the Halloween season is Stephen King’s It. A common misconception about the book is that “It” is just a scary clown — It is actually the embodiment of whatever you fear most. If what scares you the most is the possibility of ghosts, don’t worry: a researcher used acoustics analysis to explain that whatever scares you this Halloween, like It, is just a trick of the mind (and vibroacoustic effects…)

### Predicting How Long Coffee Stays Warm in a Vacuum Flask

##### Fanny Littmarck October 26, 2017

Important question: If you pour hot coffee into a vacuum flask, how long will it stay warm? There are two different modeling approaches for studying this scenario, but the more accurate method is also more computationally expensive. Let’s see what they are and when they are appropriate — and hopefully find an answer to the question.

### What Is the Physics Behind a Counterweight Trebuchet?

##### Mats Danielsson October 11, 2017

The trebuchet is a large siege weapon that you might recognize from movies set in the Middle Ages or fantasy worlds. This weapon is built on the idea of converting potential energy into kinetic energy to hurl a projectile over a large distance. Simple as it seems, the trebuchet is a complicated dynamical system. In this blog post, we will build a simplified model of a counterweight trebuchet using the Multibody Dynamics Module and examine some of its design features.

### Evaluating the Effect of Shell Thickness on Muffler Performance

##### GuestLinus Fagerberg October 3, 2017

Guest blogger Linus Fagerberg from Lightness by Design picks up where he left off in his previous blog post to discuss how radiated sound depends on the shell thickness of a muffler. Here, we discuss different entities for gauging the performance of mufflers. One important parameter is the thickness of the muffler’s casing and how this affects its performance. By performing acoustic-structure interaction simulations, we can see how shell thickness affects muffler performance.