# COMSOL Blog

## Density-Driven Fluid Flow in Porous Media

##### Alexandra Foley | July 23, 2013

There are many different forces that can induce flow in fluids, such as kinetic energy, pressure gradients, concentration gradients, and many more. In natural systems, one effect that can initiate fluid flow in a still fluid is a change in density. This density change will result in a change in the fluid’s buoyancy, thus inciting flow as the denser fluid sinks and the less dense, buoyant, fluid rises. You’re probably most familiar with these changes in density occurring due to […]

### Fatigue Prediction Using Critical Plane Methods

##### Mateusz Stec | July 22, 2013

Research on fatigue started in the 19th century, initiated following failing railroad axles that caused train accidents. In a rotating axle, stress varies from tension to compression and back to tension in one revolution. The load history is simple because it is uniaxial and proportional. Fatigue can then be evaluated with the S-N curve, also known as the Wöhler curve, which relates stress amplitude to a component’s life. In many applications we deal with multiaxiality and non-proportional loading. In this […]

### Acoustics Tutorial for Modeling Organ Pipe Design

##### Laura Bowen | July 19, 2013

The way the sound is shaped as it passes through the pipe of an organ is the result of a carefully calculated and intricate pipe design. Browsing through the Model Gallery, I came across a model of an organ pipe, and it happens to be a great acoustics tutorial for using the Pipe Acoustics, Frequency Domain interface in COMSOL Multiphysics. Let’s talk organ pipe design, and walk through how we can model it with multiphysics software.

### Simulating Thermal and Electrical Stresses in Medium Voltage Cables

##### Alexandra Foley | July 18, 2013

Underground medium voltage cables are often used to deliver electrical power from a transmission system and into the home of consumers. In the United Kingdom, these cables carry hundreds of amps at voltages between 11 and 33 kV, a typical voltage of electrical transmission cables around the world. Analyzing the stresses that these cables are exposed to over their lifetime is important for ensuring both consumer safety and energy efficiency. Researchers from the Glasgow Caledonian University in Scotland used COMSOL […]

### Highlights from Last Year’s COMSOL Conference

##### Lauren Sansone | July 17, 2013

If you want to get a sense of what the COMSOL Conference is all about before the event takes place this year, you can. We’ve gathered highlights from the COMSOL Conference 2012 so you can hear what last year’s attendees said about the event, what the keynote speakers talked about, who won Best Paper and Best Poster, and more.

### Laser Beam Welding Gets a Magnet Make-Over

##### Fanny Littmarck | July 16, 2013

Our day-to-day lives are dependent on the safety of technical systems and processes. We blindly trust that reactor vessels withstand the test of time, that the train or ship we’re on does not break down. These metal structures, in turn, rely on accurate welding processes. Here’s where BAM Federal Institute for Materials Research and Testing comes into the picture. BAM researchers have been working on improving upon the high-power laser beam welding process in order to promote safer and more […]

### What Is the Doppler Effect?

##### Alexandra Foley | July 15, 2013

The Doppler effect, or Doppler shift, is the change in wavelength and frequency caused by the movement of an observer relative to the source. One of the most common ways we can experience the Doppler effect in action is in the change of pitch that occurs due to a moving sound source. You’ve probably experienced the Doppler effect when a fire truck or ambulance passes by with its sirens blaring. As the siren passes, the pitch suddenly drops as the […]

### Past, Present, and Future of 3D Printing

##### Daniel Smith | July 11, 2013

There are many necessary steps required in order to create a superior product. Based on some initial (or existing) design, you first need to evaluate the physical characteristics of the system. Once some level of understanding of the system has been obtained, it should then be possible to refine and optimize the design based on some reasonable choice of a figure of merit for a good design. The final stage is to prototype the design, which is where 3D printing […]

### Can You Use Heat Transfer to Predict Migration of Contaminants?

##### Alexandra Foley | July 10, 2013

The flow of fluid through a porous medium is usually described by Darcy’s Law. However, what if you wanted to look at a combination of fluid flow, heat transfer, and mass transport in a porous medium? Instead of using Darcy’s Law, which calculates an average linear velocity for fluid flow in porous media, the Navier-Stokes equations would be necessary in order to obtain accurate results. In addition, heat convection and conduction, as well as mass transport would need to be […]

### Report from the Joint CAA-ASA Acoustics Conference

##### Mads Herring Jensen | July 8, 2013

Last month, the Acoustical Society of America (ASA) and the Canadian Acoustical Association (CAA) held the 21st joint meeting of the International Congress on Acoustics (ICA) in Montreal, Canada. This joint congress is one of the major acoustics conferences of 2013, featuring a range of parallel sessions that covered most topics in acoustics. These included, among other things, psycho acoustics, underwater acoustics, transducer modeling, acoustics of musical instruments, nonlinear acoustics, and many more. This year’s acoustics conference also featured a […]

### Simulating an Engine Governor, the Spring Loaded Centrifugal Governor

##### Alexandra Foley | July 5, 2013

We’ve probably all seen centrifugal force in action in one way or another, whether it be riding on a merry-go-round as a child, spinning a bucket of water upside and observing as the contents hug the insides of the bucket, or watching mud spinning off of a turning tire. In addition to making dizzying carnival rides, this force can be used in the design of many mechanical applications, where it is harnessed to control a variety of effects. One such […]