# Application Gallery

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.

Search for tutorials and apps relevant to your area of expertise via the Quick Search feature. To download the MPH-files, log in or create a COMSOL Access account that is associated with a valid COMSOL license. Note that many of the examples featured here can also be accessed via the Application Libraries that are built into the COMSOL Multiphysics® software and available from the File menu.

Acoustics Modulex

### Doppler Shift

We have all noticed the Doppler effect when an ambulance passes by with its sirens blaring. The siren’s pitch suddenly drops the moment the ambulance starts moving away from you. Another effect you can notice is how the siren’s sound is very loud when nearby, but as soon as the ... Read More

### Sub-Component Lumping in Acoustics Using the Impedance Boundary Condition

This application illustrates a modeling approach for deriving physically consistent simplified models in the Acoustics Module. The approach consists of converting complex sub-components to an impedance boundary condition and otherwise using simple acoustics throughout the COMSOL model. ... Read More

### Wax Guard Acoustics: Transfer Matrix Computation

In this tutorial, the acoustic properties of a wax guard are analyzed. A wax guard is a small perforated mesh used to protect the receiver (the miniature loudspeaker in a hearing aid) used for receiver-in-the-ear (RITE) or receiver-in-canal (RIC) hearing aids. Because of the very small ... Read More

### Test Bench Car Interior

Sound is generated by a point source located in the wall of this test bench car interior. The sound pressure level response at a point of measurement is investigated for a range of frequencies and four different mesh resolutions. The model is first solved with the default direct solvers. ... Read More

### Vibrating Plate in a 2D Viscous Parallel Plate Flow

This is a small 2D demonstration model that couples the *Linearized Navier-Stokes, Frequency Domain*, *Solid Mechanics*, and *Turbulent Flow* (k-epsilon) physics interfaces to model the vibrations of a plate located in a 2D viscous parallel plate flow. This type of model is used to model ... Read More

### Lumped Receiver with Full Vibroacoustic Coupling

When simulations are involved in the development of mobile devices, consumer electronics, hearing aids, or headsets, it is necessary to consider how the transducers interact with the rest of the system. Here, we show an analysis of the interaction between a vibration isolation mounting ... Read More

### Microphone grid free-field level correction curve for plane-wave incidence

This is a conceptual model of a microphone placed in an infinite baffle (flush mounted). The purpose is to determine the free-field level correction curve of the setup, which includes the exterior domain, microphone grid, and volume between the grid and the diaphragm. The microphone ... Read More

### 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. Read More

### Probe Tube Microphone

It is often not possible to insert a normal microphone directly into the sound field being measured. The microphone may be too big to fit inside the measured system, such as for in-the-ear measurements for hearing aid fitting. The size of the microphone may also be too large compared to ... Read More

### Acoustics of Coupled Rooms Using the Acoustic Diffusion Equation

This verification model analyzes the acoustics of two coupled rooms using the *Acoustic Diffusion Equation* interface of the Acoustics Module. The results of the model agree with analytical results that are validated against measurements in a reference paper. Read More

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