What Is the Doppler Effect?

Brianne Costa May 29, 2018

The Doppler effect, or Doppler shift, occurs when the movement of an observer relative to a source (or vice versa) causes a change in wavelength or frequency. Discovered by Austrian physicist Christian Doppler in 1803, this phenomenon is experienced in many different ways, such as when an ambulance passes you by and you hear an audible change in pitch. Using the COMSOL Multiphysics® software, you can model the Doppler effect for acoustics applications.

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Caty Fairclough April 27, 2018

Picture a classroom filled with students. At the front, a teacher discusses room acoustics, including the underlying theories and acoustics phenomena involved. To help students visualize these concepts, the teacher has created a simulation app. This app, which is accessible through a web browser, enables students to dynamically alter parameters and see the results, creating a vivid learning experience. At the Technical University of Munich (TUM), several such apps are already being used, providing benefits to teachers and students alike…

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Henrik Sönnerlind April 13, 2018

When a tuning fork is struck, and held against a tabletop, the peak frequency of the emitted sound doubles — a mysterious behavior that has left many people baffled. In this blog post, we explain the tuning fork mystery using simulation and provide some fun facts about tuning forks along the way.

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Mads Herring Jensen March 19, 2018

The boundary element method (BEM) is included in the Acoustics Module as a physics interface. This interface, available as of version 5.3a of the COMSOL Multiphysics® software, can be seamlessly combined with interfaces based on the finite element method (FEM) to model, for example, acoustic-structure interaction problems. This functionality expands the range of problems that can be solved with the Acoustics Module. Here, we look into the BEM functionality, examples, and BEM-specific postprocessing.

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Guest René Christensen February 28, 2018

Today, guest blogger René Christensen of GN Hearing discusses including thermoviscous losses in the topology optimization of microacoustic devices. Topology optimization helps engineers design applications in an optimized manner with respect to certain a priori objectives. Mainly used in structural mechanics, topology optimization is also used for thermal, electromagnetics, and acoustics applications. One physics that was missing from this list until last year is microacoustics. This blog post describes a new method for including thermoviscous losses for microacoustics topology optimization.

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Caty Fairclough January 29, 2018

Micromirrors have two key benefits: low power consumption and low manufacturing costs. For this reason, many industries use micromirrors for a wide range of MEMS applications. To save time and money when designing micromirrors, engineers can accurately account for thermal and viscous damping and analyze device performance via the COMSOL Multiphysics® software.

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Ajit Bhuddi November 8, 2017

Suppose you have a very long system with a constant cross section: a fluid-filled pipe. Modeling this system is computationally expensive and time consuming. Using a guided wave propagation approach, you can model a cross section of the system and compute the guided waves along it. You can represent such waves by means of dispersion curves. Here, we discuss a coupled analysis considering air and water as the internal fluids. We also analyze the system dynamics using dispersion curves.

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Caty Fairclough November 7, 2017

From cocktail parties to public transit, there are competing sound sources in many everyday environments. If you want to listen to one specific sound, say a friend’s question, in a complex auditory setting, you have to distinguish between the sounds around you and focus on the one of interest. This situation is known as “the cocktail party problem”. Understanding how humans solve this problem can lead to advancements in hearing aid designs.

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Caty Fairclough November 1, 2017

You’re listening to music when you bump into your loudspeaker, knocking it off the table. Fortunately, it still works! In his keynote presentation at the COMSOL Conference 2017 Boston, Richard Little discussed how Sonos, Inc. ensures that loudspeakers are durable enough to withstand certain stresses and how they use simulation to improve the robustness of the transducer component. If you missed his talk, you can watch the video recording below, followed by a quick summary of his presentation.

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Brianne Costa October 31, 2017

My favorite novel to read around the Halloween season is Stephen King’s It. A common misconception about the book is that “It” is just a scary clown — It is actually the embodiment of whatever you fear most. If what scares you the most is the possibility of ghosts, don’t worry: a researcher used acoustics analysis to explain that whatever scares you this Halloween, like It, is just a trick of the mind (and vibroacoustic effects…)

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Guest Linus Fagerberg October 3, 2017

Guest blogger Linus Fagerberg from Lightness by Design picks up where he left off in his previous blog post to discuss how radiated sound depends on the shell thickness of a muffler. Here, we discuss different entities for gauging the performance of mufflers. One important parameter is the thickness of the muffler’s casing and how this affects its performance. By performing acoustic-structure interaction simulations, we can see how shell thickness affects muffler performance.

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