# 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.

### Applying a Current-Voltage Switch to Models

This example exemplifies how to model the switching between current and voltage excitations in *Terminal* boundary conditions. A more detailed description of the phenomenon and the modeling process can be seen in the blog post "[Control Current and Voltage Sources with the AC/DC Module](https://www.comsol.com/blogs/control-current-and-voltage-sources-with-the-acdc-module/)".

### Finding the Impedance of a Parallel-Wire Transmission Line

A parallel wire transmission line is composed of two conducting wires in a dielectric such as air. The fields around such a transmission line are not directly confined by the conductors, and extend to infinity, although they drop off in rapidly away from the wires. This model demonstrates how to compute the fields and impedance of such an unshielded transmission line, and compares to the ...

### Natural convection in a closed cavity with mass conservation

Only fully compressible flow can guarantee the mass conservation in time in a closed cavity where the temperature increases. This is a simple proof of concept using the "gravity" option available in V5.2A.

### Electrode Utilization in a Large Format Lithium-Ion Battery Pouch Cell

Large lithium-ion batteries are widely deployed in electric vehicles and for stationary energy storage applications. In the (stacked) pouch battery cell design, all current exits the cell on the cell “tabs”, and as the cell size and power increases, the voltage gradients in the highly conductive metal foil current collectors may come into play, resulting in a non-uniform current distribution and ...

This model shows how to use the Mathematical Particle Tracing interface to simulate mixed diffuse-specular reflection between surfaces in an enclosure. This model is separated in two parts. The first part compares the heat fluxes computed by the Mathematical Particle Tracing interface with the exact solution for two identical infinitely long parallel grey plates under mixed diffuse-specular ...

### Truss Bridge Designer

The Truss Bridge Designer app is an example of how to design a simulation tool for a class of civil engineering structures, in this case a Pratt truss bridge. Such a bridge is characterized by the diagonal beams on each side of the bridge, which all slant down and in toward the center of the span. Because of this design, the diagonal beams are subjected only to tension, while the vertical beams, ...

### Combining Elastoplastic and Creep Material Models

This model shows how to combine different types of material nonlinearity, such as creep and elastoplasticity. In this specific example you will perform a stress and nonlinear strain analysis on a thick cylinder under a nonproportional loading: an initial temperature increase followed by a fluctuating pressure applied to the internal surface of the cylinder. This load case involves two ...

### Apartment Acoustics Analyzed using the Acoustic Diffusion Equation

The sound distribution from a TV in a two-room apartment is computed. The simulation demonstrates the use of the Acoustic Diffusion Equation interface to get a quick and simple estimate of the local sound pressure level. For increased accuracy, an analytical expression for the direct sound is added in the living room.

### Fundamental Eigenfrequency of a Rotating Blade

High rotational speed in rotating machineries can result in centrifugal forces of considerable magnitude. The forces induced by the rotation give rise to two counteracting effects: stress-stiffening and spin-softening (or centrifugal softening). The former is caused by the stationary stress field created by the centrifugal force and acts to increase the stiffness of the body, and so increase its ...

### Dipolar Microwave Plasma Source

This model presents a 2D axisymmetric dipolar microwave plasma source sustained through resonant heating of the electrons. This is known as electron cyclotron resonance (ECR), which occurs when a suitable high magnetic flux density is present along with the microwaves. This is an advanced model that showcases many of the features that make COMSOL unique, including: Infinite elements for the ...

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