# 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.

### 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 ...

### Acoustic Reflections off a Water-Sediment Interface

This model determines the reflection coefficient of plane acoustic waves, at different frequencies and at different angles of incidence, off a water-sediment interface. The ability of the Poroelasitc Waves interface to model the coupled acoustic and elastic wave in any porous substance (Biot's theory) is used to describe the water-sediment system. The model results are in good agreement with ...

### 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 *Creeping Flow* 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 fluid-structure interaction (FSI) in the frequency domain. For simplicity, the flow is assumed to be a creeping flow. ...

### Noise Radiation by a Compound Gear Train

Predicting the noise radiation from a dynamic system gives designers insight into the behavior of moving mechanisms early in the design process. For example, consider a gearbox in which the change in the gear mesh stiffness causes vibrations. These vibrations are transmitted to the gearbox housing through shafts and joints. The vibrating housing further transmits energy to the surrounding fluid, ...

### Axisymmetric Condenser Microphone

This is a model of a condenser microphone with a simple axisymmetric geometry. The model aims to give a precise description of the physical working principles of such a microphone. The condenser microphone is considered to be the microphone with highest quality when performing precise acoustical measurements and with high-fidelity reproduction properties when performing sound recordings. This ...

### 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 ...

### 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 ...

### Spherical Scatterer: BEM Benchmark

In this classical benchmark model, a spherical scatterer is placed in a plane wave background field. When the sphere is modeled as sound hard, the problem has an analytical solution. The model compares the results using the *Pressure Acoustics, Boundary Elements* interface with the analytical solution for several frequencies. The results show very good agreement. The model results do not show ...

### Loudspeaker Radiation: BEM Acoustics Tutorial

In this tutorial, the acoustic radiation pattern from a small generic loudspeaker is analyzed using the boundary element method (BEM). The loudspeaker is located on a small table above the floor and at a given distance from a wall. The model is set up using the *Pressure Acoustics, Boundary Elements* physics interface of the Acoustics Module. The model shows the basics of setting up such an ...

### Anechoic Coating

Anechoic coatings are used for lowering visibility to sonars, for example on submarines. This model calculates the reflection, absorption, and transmission properties of an anechoic coating on a steel plate based on a setup from literature.

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