# 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.

### Helmholtz Resonator Analyzed with Different Frequency Domain Solvers

This model simulates a simple three-dimensional axisymmetric Helmholtz resonator, a classic acoustics model of a resonating circuit with a known theoretical solution. The idealized version considered here consists of a tube and a closed volume in series which are exposed to a pulsatile pressure. Real-world phenomena explained by the resonator include amongst others the resonance from blowing ...

### Acoustic Scattering off an Ellipsoid

This is a tutorial model that illustrates the use of the scattered field formulation in acoustics. A solid object (here an ellipsoid) is hit by an incident plane wave field (background pressure field). The model solves for the scattered field. The model uses a PML and a far-field calculation is also added. The mesh is set up to enhance the PML and the far-field performance.

### Focused Ultrasound Induced Heating in Tissue Phantom

This model example shows how to model tissue heating induced by focused ultrasound. First, the stationary acoustic field in the water and the tissue are modeled to obtain the acoustic intensity distribution in the tissue. The absorbed acoustic energy is then calculated and used as the heat source for a Bioheat Transfer physics in the tissue domain in a time-dependent study simulating the ...

### Submarine Scattering: Time-Domain Simulation and FFT

This model analyzes the scattering of a plane wave off a submarine hull. The scattered field and the spatial response are also determined. The model uses the *Pressure Acoustics, Time Explicit* interface to model this large acoustic model in the time domain. Then, a *Time to Frequency FFT* study is used to transform the results into the frequency domain and the scattered field is analyzed with ...

### 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.

### Open Pipe

In this model, sound created by a vibrating piston radiates through a baffled pipe. The impedance is measured and then used in an impedance boundary condition that replaces the surrounding air domain. This technique can be employed to reduce solution time and memory usage for large models with pipe openings.

### Plane Wave Scattering off a 2D Axisymmetric Object: Plane Wave Expansion Approach

The problem of a plane wave scattering off a cylinder-shaped object suggests the use of the 2D axisymmetric formulation. This can save computation time and reduce the memory usage compared to the model in 3D space. This example demonstrates the use of the built-in plane wave expansion functionality to solve the problem. It also highlights the steps required during the study and the ...

### Tonpilz Transducer Array for Sonar Systems

This model sets up a linear array of nine tonpilz piezoelectric transducers in a 3x3 grid. A voltage is applied that includes a phase change across the three rows. The transducers are located in a box below the sea surface. The exterior acoustics are modeled using the *Pressure Acoustics, Boundary Elements* interface, which is coupled to the vibrating structures with the *Acoustic-Structure ...

### Acoustic Reflection Analyzer for a Water-Sediment Interface

Analyzing acoustic reflections at surfaces of various structures is important for many engineering disciplines. The Acoustic Reflection Analyzer for a Water-Sediment Interface app shows one such system where the analysis has relevance for underwater acoustics and sonar applications. The app analyzes the reflection and absorption coefficients of plane acoustic waves, scattering off of a water ...

### Baffled Membrane

Learn how to use the Acoustic-Shell Interaction interface in this tutorial example of a thin vibrating membrane set in an infinite baffle. This example demonstrates how to model the acoustic interaction between a vibrating membrane and the surrounding air. In order to focus on the principles, the geometry is kept simple and the driving mechanism is not modeled.

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