Modeling Aeroacoustics with the Linearized Navier-Stokes Equations

Mads Herring Jensen July 25, 2017

Detailed modeling of the complex interaction of flow and acoustics is achieved in the COMSOL Multiphysics® software and add-on Acoustics Module using the linearized Navier-Stokes interfaces. With the release of version 5.3, the capabilities were further extended with the addition of a new stabilization scheme. This allows robust simulations of systems with acoustic properties that are modified by or depend on a turbulent background flow; e.g., automotive exhaust systems. Here, we introduce important modeling concepts and present application examples.

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Bridget Cunningham July 10, 2017

Of the 72 million potential hearing aid users around the world, each needs a device fitted to meet their needs. In-the-ear measurements are performed to ensure both comfort and effectiveness. These measurements require the use of a microphone — the size of which can cause issues. The device can be too large to fit into the measured sound field. Alternatively, it can be too big compared to the wavelength and disturb the acoustic field. One solution is a probe tube…

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Pawan Soami May 23, 2017

Gears are used in a variety of applications, such as clocks, industrial machinery, music boxes, bicycles, and automobiles. A gearbox is a major source of vibration and noise irrespective of how it is used. The most effective approach to reduce the noise radiation from a gearbox is to perform a vibroacoustic analysis to improve the design. Let’s see how the COMSOL Multiphysics® software can be used to help build quieter transmission systems.

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Caty Fairclough March 17, 2017

When simulating hearing aids, it’s important to determine how transducers interact with the rest of the system. In some cases, these studies require fully detailed models, increasing their computational cost. One alternative is coupling a lumped parameter transducer model with a multiphysics model representing the whole system. In this blog post, we discuss the example of a Knowles ED-23146 receiver (or miniature loudspeaker) that is connected to a test setup and compare the results to measurement data.

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Mads Herring Jensen January 26, 2017

Modeling acoustically large problems requires a memory-efficient approach like the discontinuous Galerkin method. To make solving these types of problems easier, we’ve added a new physics interface based on this method to the Acoustics Module: the Convected Wave Equation, Time Explicit interface. It can include a stationary background flow and is suited for modeling linear ultrasound applications. Today, we will explore how to use this interface with the example of an ultrasound flow meter.

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Caty Fairclough January 19, 2017

For those looking to solve complex transport process problems involving photonics and microfluidics, it can be challenging to account for all of the elements involved, including multiple physics phenomena. However, this is necessary for accurate results. By using multiphysics simulation, Carl Meinhart from the University of California, Santa Barbara and Numerical Design, Inc. accurately modeled transport processes in two application areas: high-frequency acoustics and microfluidic valves. Watch his keynote talk from the COMSOL Conference 2016 Boston to get the details.

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Bridget Paulus January 16, 2017

When a pipe springs a leak, it’s important to find its location with a quick and accurate method. Engineers at Echologics — a Mueller Technologies Company — use a combination of acoustic sensors and simulation applications to pinpoint such leaks. Sebastien Perrier of Echologics discussed the benefits of this approach and gave a live demonstration of an acoustics modeling app during his keynote talk at the COMSOL Conference 2016 Boston. If you missed Sebastien’s presentation, you can watch it below.

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Linus Andersson January 5, 2017

Dolphins and bats have relied on echolocation for millions of years. Yet, it would take until the early 1900s before humans first developed and used sonar. Not long after came the first countermeasure: the anechoic coating. Today, we’ll look at how you can model the reduction in echo that this provides using COMSOL Multiphysics®. Similar modeling techniques can also be used for other periodic structures, such as perforates, phononic crystals, and various sound absorbers.

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Guest René Christensen November 3, 2016

Today, guest blogger René Christensen of GN ReSound discusses the importance of acoustic topology optimization and how to apply it in COMSOL Multiphysics. Topology optimization is a powerful tool that enables engineers to find optimal solutions to problems related to their applications. Here, we’ll take a closer look at topology optimization as it relates to acoustics and how we optimally distribute acoustic media to obtain a desired response. Several examples will further illustrate the potential of this optimization technique.

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Caty Fairclough November 1, 2016

Ocean acoustic tomography systems measure temperature using an acoustic signal that travels between two instruments. These systems often need to cover a broad frequency band with low-frequency signals and require a high-power sound source. One option to achieve these goals is a tunable organ pipe, which balances efficiency and functionality. A researcher at the Advanced Technology Group, Teledyne Marine Systems used simulation to improve his tunable organ pipe design and compared the results to experimental tests.

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Linus Andersson September 29, 2016

Perforations, in mufflers for example, enable partial sound transmission between chambers as well as in and out of pipes. When simulating perforates, it’s possible to draw and mesh each hole, but this increases the time it takes to solve the model. For a more efficient approach, we can apply a semitransparent boundary. Here, we’ll discuss several techniques for doing so as well as describe a method for computing the transfer impedance of the perforate.

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