Acoustics

Mads Herring Jensen | February 28, 2014

Previously, we introduced the theory behind thermoacoustics. Here, I will go deeper into modeling acoustics with the Thermoacoustic interface in COMSOL Multiphysics and show you some tips and tricks on how to do this.

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Mads Herring Jensen | February 27, 2014

When sound propagates in structures and geometries with small dimensions, the sound waves become attenuated because of thermal and viscous losses. More specifically, the losses occur in the acoustic thermal and viscous boundary layers near the walls. This is a known phenomenon that needs to be included when studying and simulating systems affected by these losses in order to model these systems correctly and to match measurements.

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Mads Herring Jensen | January 2, 2014

I recently had the pleasure of preparing a small contribution to the 166th Meeting of the Acoustical Society of America (Fall 2013) together with Wade Conklin and Jordan Schultz from Knowles Electronics. Wade presented our paper entitled “Characterization of a microelectromechanical microphone using the finite element method”. The work consisted of implementing a virtual prototype of a Knowles MEMS microphone (the SPU0409LE5H microphone, see picture below) using COMSOL Multiphysics.

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Andrew Griesmer | September 19, 2013

When performing an analysis on small-scale audio equipment, such as hearing aids, cell phones, and microphones, the obvious physical phenomenon that’s analyzed is pressure acoustics. However, there are other physics interactions that significantly affect these small devices, including electromechanical interactions and viscothermal losses. Most notably, thermoacoustics (the detailed modeling of acoustics including thermal conduction and viscous losses) is an often overlooked effect that can alter the results of a model. These effects are important in all devices with small length […]

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Supratik Datta | August 26, 2013

If you have ever stood next to a transformer, you have probably heard a humming sound coming from it and wondered if there were bees close by. When you hear that sound the next time, you can rest assured that it’s not bees but the magnetostriction of the transformer core that is making that humming sound.

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Bethany Moatts | August 14, 2013

Multiphysics applications are all around us. Consider, for example, a setting where science may be the last thing on our minds: a music concert. You might be enjoying the slight sinusoidal variations in atmospheric pressure we call sound waves, or music, but those pressure variations must come from somewhere. In fact, they are due to a multiphysics effect where sinusoidal structural vibrations in an object disturb the surrounding air, causing pressure variations in the air that then propagate outward and […]

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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.

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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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