Acoustics

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 […]

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Mads Herring Jensen | May 23, 2013

Mufflers are often located in exhaust systems or on heat, ventilation, and air conditioning (HVAC) systems, where their key functionality is to dampen the noise that is emitted from the system. A correct description of the acoustic damping (absorption and attenuation) processes in the muffler is important when designing and modeling these systems.

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Bethany Moatts | April 12, 2013

When given the choice, we’d all prefer our loudspeakers to project perfect sound; having a phone conversation with someone who sounds like a robot caught in a windstorm is less than ideal. The quality of the sound is, naturally, dependent on how well the speaker is designed, and COMSOL Multiphysics is the perfect tool to simulate and optimize loudspeaker designs because of its easy-to-use multiphysics nature. For a loudspeaker analysis to be accurate, you must be able to simulate from […]

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Mads Herring Jensen | March 7, 2013

The use of acoustic waves to manipulate suspensions of particles, such as cells, has inspired the work of many researchers, paving the way for the field of ultrasound acoustofluidics. The manipulation is achieved in many ways, including using bulk acoustic waves (BAW) and surface acoustic waves (SAW), as well as acoustic radiation forces and acoustic streaming-induced drag. The latter two combine to produce the acoustophoretic motion of the suspended particles; i.e., movement by means of sound, and the methods provide […]

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Andrew Griesmer | December 18, 2012

SOund NAvigation Ranging, or Sonar, has been an important part of naval warfare and since the 1950’s. Although it is a relatively simple way to locate objects, it’s the best for doing so in water, emitting sound waves and listening for echoes made by objects in the water. In today’s world of undersea warfare, the threats and the necessary responses to them are becoming more important and urgent. Sonar systems are required to detect these threats, making it necessary for […]

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Fanny Littmarck | December 12, 2012

A while back, I wrote about permanent magnet generators and how they generate electricity upon being set in motion. When browsing the papers from our conference in Bangalore, one on the topic of ultrasonic micro motors caught my eye. These motors are electromechanical in nature and instead initiate motion with the application of an electric voltage. Furthermore, these motors are miniaturized to fit a micro-scale environment.

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Phil Kinnane | April 9, 2012

Wind turbines are an expensive investment and once they’re up, they’re up. An article from last year’s COMSOL News points to how modeling can also help in remedying problems, if it’s too late to have built the perfect design from the beginning. With wind turbines, noise is of course the problem.

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Phil Kinnane | April 4, 2012

I had previously blogged about Thermal Cloaking, which uses layers of aluminum and paper to create an anisotropic structure and cloak a desired object. This differs from the “traditional” type of cloaking, of light and electromagnetic waves, which make use of metamaterials or layered structures that impose a negative refractive index to make the cloaked object appear transparent.

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Phil Kinnane | March 19, 2012

While you may think that the prevalence of lightning strikes, would be a reason for not wanting wind turbines in your backyard, noise is apparently another reason. While this has become less of a problem in recent years, the noise is still there, and is always there whenever the wind blows.

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Phil Kinnane | March 8, 2012

Many devices live with a dry, technical name that either basically says what the device does, or is an acronym of that dry, technical name. Very few get a nickname that sticks to become the industry standard.

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