## Simulating Viscous Heating in a Fluid Damper

##### Brianne Costa September 9, 2015

Fluid dampers have a range of uses, from stabilizing skyscrapers to controlling fluid flow in microflow devices. Through a process called viscous heating, these dampers are able to dissipate mechanical energy into heat. Too much heat can cause damage to the damper, so it’s important to understand the viscous heating process when optimizing your fluid damper designs.

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##### Walter Frei September 8, 2015

Good competitive paddling requires strength, timing, consistency, and teamwork. Initially, this may seem quite easy. Simply stick your paddle in the water and make the water go backward so that the boat moves forward. As it turns out, there are actually many different paddling strokes you can use depending on the situation.

### Deformed Mesh Interfaces: Rotations and Linear Translations

##### Walter Frei September 7, 2015

When using the finite element method, we often want to model solid objects that are rotating and translating within other domains. The deformed mesh interfaces in COMSOL Multiphysics can be used to model these movements. In this blog post, we will look at the modeling of large linear translations and rotations of domains within other domains, while introducing efficient modeling techniques for addressing such cases.

### Model Translational Motion with the Deformed Mesh Interfaces

##### Walter Frei September 4, 2015

COMSOL Multiphysics includes two interfaces for manually defining the deformation of finite element mesh, the Deformed Geometry interface and the Moving Mesh interface. In this blog post, we will address when to use these interfaces and how to use them to efficiently model translational motion.

### Improving Your Meshing with Swept Meshes

##### Walter Frei September 2, 2015

Modeling geometries with high aspect ratios can be one of the more challenging tasks for the finite element analyst. You want to have a mesh that will accurately represent the geometry and the solution, but you do not want too many elements, as solving your models would then require excessive computational resources. Here, we will look at using swept meshing to generate efficient and accurate finite element meshes in the context of some common modeling cases.

### How to Organize Your Simulation App Using Subforms

##### Bridget Cunningham September 1, 2015

An important element in the design of any simulation app is organization. Maintaining an orderly structure makes it easier for you to build the app and also enhances the usability experience for app users. Today, we will show you how to create organized apps in COMSOL Multiphysics with the help of subforms and form collections.

### Focusing on an Electrowetting Lens

##### Caty Fairclough August 31, 2015

Adjusting the focal length of a camera lens allows you to change your angle of view. Miniature lenses can achieve this change by using a method called electrowetting. Electrowetting involves changing the balance of forces at a contact point of a free surface and a solid by applying a voltage. However, focus is not obtained immediately due to oscillations in the free surface. Here, we investigate the optimal viscosity for critically damping the free surface when a voltage is applied.

### The Physics of Tennis Racket Sweet Spots

##### Fabio Bocchi August 27, 2015

Each year, tennis players from around the world compete at the U.S. Open, one of the oldest and largest tennis tournaments. With the 2015 tournament approaching, I found myself reflecting on my own experiences playing tennis, particularly how the feeling you get after hitting the ball is never quite the same. Is this simply a figment of the imagination or is there a physical answer? As I will explain here, so-called “sweet spots” can account for this feeling.

### Creating Ultrafast Polymerase Chain Reaction Tests with LEDs

##### Bridget Cunningham August 26, 2015

Polymerase chain reaction tests have many applications within medical and biological research. In the past, these tests have been performed within a laboratory setting due to their high power requirements and the slow speed at which results are delivered. Researchers at the University of California, Berkeley have developed a new LED-based polymerase chain reaction system that, with its simplicity and speed, could be used in point-of-care testing.

### Simulation Apps: How to Add a File Menu with Save Options

##### Andrew Griesmer August 25, 2015

When a user running your COMSOL app finds a particularly interesting set of results, they might need to save their app so they can come back to it later. Without save options, you’d have to re-run the simulation later with the input parameters they gave you. That would be very inefficient and defeat the purpose of creating simulation apps. Today, we’ll show you how to add a file menu with save options in your app.

### How to Implement a Point Source with the Weak Form

##### Chien Liu August 24, 2015

Today we continue our discussion on the weak formulation by looking at how to implement a point source with the weak form. A point source is a useful tool for idealizing the situation where a source is concentrated in a very small region of the modeling domain. We will find that it is very convenient to set up such a point source using the weak form.

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