Acoustics

Alon Grinenko | May 20, 2015

In an earlier blog post, we considered the computation of acoustic radiation force using a perturbation approach. This method has the advantage of being both robust and fast; however, it relies heavily on the theoretical evaluation of correct perturbation terms. The idea behind the method presented here is to solve the problem by deducing the radiation force from the solution of the full nonlinear set of Navier-Stokes equations, interacting with a solid, elastic microparticle.

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René Christensen | April 21, 2015

Today we welcome guest blogger René Christensen from Dynaudio A/S. When evaluating loudspeaker performance, dips and/or peaks in the on-axis sound pressure level can be a result of an unfortunate distribution of phase components. To overcome this, we use a phase decomposition technique that splits a total surface vibration into three components depending on how they contribute to the sound pressure in an arbitrary observation point; either adding to, subtracting from, or not contributing to the pressure.

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Chien Liu | April 1, 2015

Over half a century ago, Mark Kac gave an interesting lecture on a question that he had heard from Professor Bochner ten years earlier: “Can one hear the shape of a drum?” He focused on the (then undetermined) uniqueness of the set of eigenvalues given the shape of a vibrating membrane. The eigenvalue problem has since been solved and here we explore the “hearing” part of the question by considering some interesting physical effects.

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Mads Herring Jensen | February 25, 2015

When inside a room — a conference room, concert hall, or even a car — everyone has an opinion of when the “acoustics” are good or bad. In room acoustics, we want to study this notion of sound quality in a quantitative way. In short, room acoustics is concerned with assessing the acoustics of enclosed spaces. The Acoustics Module of COMSOL Multiphysics has several tools to simulate the acoustics of rooms and other confined spaces. I will present those here.

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Alon Grinenko | January 29, 2015

Acoustic radiation force is an important nonlinear acoustic phenomenon that manifests itself as a nonzero force exerted by acoustic fields on particles. Acoustic radiation is an acoustophoretic phenomenon, that is, the movement of objects by sound. One interesting example of this force in action is the acoustic particle levitation discussed in this previous blog post. Today, we shall examine the nature of this force and show how it can be computed using COMSOL Multiphysics.

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Supratik Datta | December 30, 2014

We have introduced a new interface for simulating piezoelectric devices in version 5.0 of the COMSOL Multiphysics simulation software. This interface aims to achieve several things. In this blog post, I will explain what these things are and how you can use them.

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Christopher Boucher | November 26, 2014

With the release of COMSOL Multiphysics version 5.0, the Particle Tracing Module now includes a series of features called Accumulators, which can be used to couple the results of a particle tracing simulation to other physics interfaces. The accumulated variables may represent any physical quantity and can be defined either within domains or on boundaries, making them extremely flexible. Here, I will explain the different types of accumulators and their applications in particle tracing and ray optics models.

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Bridget Cunningham | November 17, 2014

The reduction of aircraft engine noise has been a priority in the aviation industry for many years. Minimizing sound emissions, of course, requires an understanding of engine noise — a task that can become quite challenging due to the complex nature of aircraft systems and geometries. Using a model of an aero-engine duct, we provide a more in-depth look at the acoustical field in aircraft engines.

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Laura Bowen | July 16, 2014

The need for a contaminant-free space to manufacture medicine has led scientists to try many creative new approaches to improve the process. At Argonne National Lab, creating a device that floats and rotates chemical compounds in thin air was just the answer they were looking for. It meant two important changes: the amount of each chemical necessary could be implemented very precisely and the risk of outside impurities disrupting the results was minimized.

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Fanny Littmarck | June 26, 2014

Sound Navigation and Ranging (SoNaR, more commonly written in all lowercase as “sonar”) technology can be used for investigating and communicating underwater. To improve the sonar system, you need to optimize the design at a component level. A major component of sonar is the electro-acoustic transducer.

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Alexandra Foley | June 25, 2014

Wind turbine noise is a (hotly disputed) topic that we’ve mentioned on the blog before. While research into noise production by wind farms is still being debated among researchers, one way we’ve found to overcome these noisy turbine troubles is to place turbines offshore where they can’t be heard and, conveniently, high winds with more regularity make energy production more effective. However, a question that comes to mind is: What impact do offshore wind farms have on marine life?

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