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The Model Gallery features COMSOL Multiphysics model files from a wide variety of application areas including the electrical, mechanical, fluid, and chemical disciplines. You can download ready-to-use models and step-by-step instructions for building the model, and use these as a starting point for your own modeling work. Use the Quick Search to find models relevant to your area of expertise, and login or create a COMSOL Access account that is associated with a valid COMSOL license to download the model files.

Vibrating Micromirror with Viscous and Thermal Damping

Micromirrors are used in certain MEMS devices to control optic elements. This model of a vibrating micromirror surrounded by air uses the Thermoacoustic-Shell Interaction user interface to model the fluid-solid interaction, and it thus includes the correct viscous and thermal damping of the mirror from the surrounding air. The resonance frequency of the mirror when under a torquing load is ...

Acoustic Cloaking

Two articles in the New Journal of Physics describe how to derive necessary conditions on an anisotropic density tensor to create a perfect acoustic cloak in 2D, and show how this material can be realized in practice as a layered shell with isotropic properties in each layer. These two example files illustrate simplest possible implementations using both anisotropic density and the layered ...

Vibrations of a Disk Backed by an Air-Filled Cylinder

The vibration modes of a thin or thick circular disc are well known, and it is possible to compute the corresponding eigenfrequencies to arbitrary precision from a series solution. The same is true for the acoustic modes of an air-filled cylinder with perfectly rigid walls. A more interesting question to ask is: What happens if the cylinder is sealed in one end not by a rigid wall but by a thin ...

Radially Polarized Piezoelectric Transducer

This tutorial model shows how a user-defined coordinate system can be used to create any type of directional polarization of a piezoelectric material. Results are shown for the case of radial polarization of a piezoelectric disk. The piezoelectric material is PZT-5H. The example shows a static analysis. Visualization of the cylindrical coordinate system as well as the stress/strain in that system ...

Tuning Fork with Acoustics

Acoustic-Structural Interaction in a Tuning Fork This model simulates a tuning fork for tuning musical instruments which, if correctly designed, should sound the note of A, 440 Hz. First an eigenfrequency analysis is performed on this structure to ensure its fundamental frequency is exactly 440 Hz. Then the interaction between the structural vibrations in the tuning fork and the acoustic ...

Uniform Layer Waveguide

Whenever dimensions in waveguides become small compared to the viscous and thermal boundary layers it is necessary to model acoustics using thermoacoustics. In the present model the thermoacoustic wave field in a shallow uniform waveguide is modeled and compared to an analytical solution.

Point Source in 2D Jet: Radiation and refraction of sound waves through a 2D shear layer

This is a benchmark model for the linearized Euler interface of the Acoustics Module. The model is from the NASA "Fourth Computational Aeroacoustics (CAA) Workshop on Benchmark Problems (2004)". The model results are compared to an analytical solution by Agarwal et al. (AIAA Vol. 42, No. 1, January 2004). A point source is located in a narrow 2D jet of Mach 0.8. The model investigates the ...

Cylindrical Subwoofer

In this model, the acoustic field inside and outside a down-firing subwoofer is computed. This model is set up in 2D axisymmetry using the Pressure Acoustics application mode. The modeled physical domain is a hemisphere with a radius of 1 m. To minimize the effect of non-physical reflections at the exterior boundary of this domain, an absorbing Perfectly Matched Layer (PML) is added. 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 thermoacoustic interface with a ...

Acoustic Muffler with Thermoacoustic Impedance Lumping

This model utilizes the thermoacoustic interface in a submodel to obtain a detailed (and more precise) measure for the transfer impedance of a perforated plate. The impedance is in turn used as an internal impedance in a pressure acoustic model of a muffler. Results are compared to classic impedance models.

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