The Application Gallery features COMSOL Multiphysics® tutorial and demo app files pertinent to the electrical, structural, acoustics, fluid, heat, and chemical disciplines. You can use these examples as a starting point for your own simulation work by downloading the tutorial model or demo app file and its accompanying instructions.

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Nonlinear Acoustics — Modeling of the 1D Westervelt Equation

This model example shows how to model nonlinear propagation of 1D finite-amplitude Acoustic waves in fluids using Acoustics Module of COMSOL Multiphysics. The model is based on the 2nd order Westervelt equation. The one dimensional nonlinear wave equation is solved in the time domain by adding the nonlinear term to the linear equation. The model does not include energy dissipation in order to ...

One-Family House Acoustics

This model shows an application of the Acoustic Diffusion Equation physics interface. The acoustics in a two story one-family house consisting of 10 rooms is analyzed. The steady state sound pressure level (acoustic energy density) distribution is analyzed for a sound source located in the main living room. The reverberation time T60 of the different coupled rooms is then studied using the ...

Photoacoustic Resonator

This is a model of a simple photoacoustic (or optoacoustic) resonator. A pulsating laser heats a gas causing expansion and contraction and thus creates pressure waves. Such devices are used as sensors for measuring material parameters of the gas inside the resonator. The resonance frequency of the system depends on the gas in the resonator. The model uses the Thermoviscous Acoustic, Frequency ...

Muffler with Perforates

Reflective mufflers are best suited for the low-frequency range where only plane waves can propagate in the system, while dissipative mufflers with fibers are efficient in the mid- to high-frequency range. Dissipative mufflers based on flow losses, on the other hand, also work at low frequencies. A typical automotive exhaust system is a hybrid construction consisting of a combination of ...

Acoustics of a Pipe System with 3D Bend and Junction

This tutorial shows how to model the propagation of acoustic waves in large pipe systems by coupling the *Pipe Acoustics* interface to the *Pressure Acoustics* interface. The tutorial is set up in both the time domain and the frequency domain. 1D pipe acoustics is used to model the propagation in the long straight pipe portions. A 3D model of a pipe junction and pipe bend is coupled to the 1D ...

Shape Optimization of a Tweeter Waveguide

This application illustrates how to use COMSOL’s optimization capabilities to automatically develop novel designs satisfying critical design constraints. The model optimizes a simple speaker geometry. Examples of constraints could include the radius of the loudspeaker or a desired minimum achievable sound-pressure level. To exemplify the optimization capabilities this application studies the ...

Multilayered Porous Material: Poroelastic Waves with Thermal and Viscous Losses (Biot-Allard Model)

In applications where pressure and elastic waves propagate in porous materials filled with air, both thermal and viscous losses are important. This is typically the case in insulation materials for rooms, lining materials in car cabins, or foams used in headsets and speakers. Another example is porous material in mufflers in the automotive industry. In many cases, these materials can be modeled ...

Small Concert Hall Acoustics

Designing structures and open spaces with respect to sound quality is important for concert halls, outdoor environments, and even the rooms of a house. Simulating acoustics in the high-frequency limit, where the wavelength is smaller than the geometrical features, can be done with ray acoustics. There are several advantages to modeling ray acoustics, including changing media properties and ...

Piezoelectric Tonpilz Transducer with a Prestressed Bolt

A tonpilz transducer is used for relatively low frequency, high power sound emission. It is one of the popular transducer configurations for SONAR applications. The transducer consists of piezoceramic rings stacked between a head mass and a tail mass which are connected by a central bolt. This example shows how to incorporate the effect of a pre-tension in the bolt. The bolt geometry is ...

Spherical Piezoacoustic Transducer

This tutorial provides a step-by-step instruction to setup a fully-coupled 3D structural-acoustic interaction problem. Interaction between a vibrating spherical piezoelectric structure with the surrounding fluid media is considered. The piezoelectric material PZT-5H from the materials library is used. Instructions on how to create a radially polarized piezoelectric material in spherical ...