# 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.

### Linear Magnetic Gear

In this model, a linear magnetic gear system with a gear ratio of 11:4 is modeled. The liner magnetic gear is assumed to be infinitely long with the modular structure that is repeating on either side. Only a single modular section is modeled by using the customized linear periodic boundary condition. Both the low speed and the high speed armatures (rotors) consist of permanent magnets and back ...

### Optimal Cooling of a Tubular Reactor

Maximizing product yield is a main task in chemical reaction engineering. This can be especially challenging if the desired product, once formed, can be consumed by further reactions. This example investigates such a series reaction as it occurs in a tubular reactor. You will start by setting up the tightly coupled mass and energy balance equations describing the reactor using predefined ...

### Molecular Flow Through an S-Bend

This model computes the transmission probability through an s-bend geometry using both the angular coefficient method available in the Free Molecular Flow interface and a Monte Carlo method using the Mathematical Particle Tracing interface. The computed transmission probability by the two methods is in excellent agreement with less than a 1% difference. This model requires the Particle Tracing ...

### 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 ambulance has passed the sound becomes much quieter. This model simulates the acoustic Doppler effect by placing ...

### Viscous Catenary

The catenary is the geometrical shape that corresponds to the curve followed by an idealized chain or cable supported at both ends and hanging under its own weight. The viscous catenary problem describes the motion of a cylinder of highly viscous fluid, supported at its ends as it flows under gravity. In the last decade this problem has generated significant theoretical and experimental interest ...

### Contact Analysis of a Snap Hook Using a Penalty Formulation

This example simulates the insertion of a snap hook in its groove. Here, the purpose of the contact modeling is only to transmit correct contact forces in a global sense into the model, which is a situation well suited for using the penalty method. This contact algorithm is based on the penalty factor formulation related to the penetration of the solid parts in contact. In some cases, this ...

### Transmission Line Butler Matrix Beamforming Network

A Butler matrix is a passive beamforming feed network. It is a cost-effective feed network for phased array antennas because the circuit can be fabricated in the form of microstrip lines and is a viable solution for performing beam scanning without deploying expensive active devices. This example shows how to design such a circuit using the *Transmission Line* interface. The results show the ...

### Small Signal Analysis of a MOSFET

This model shows how to compute the AC characteristics of a MOSFET. Both the output conductance and the transconductance are computed as a function of the drain current.

### 1D Isothermal Lithium-Air Battery

Rechargeable lithium-air batteries have recently attracted great interest mainly due to their high energy density. The theoretical value is about 11400 Wh/kg which is around 10 times greater than the lithium-ion batteries. In this tutorial, discharge of a lithium-air battery is simulated using the *Lithium-ion Battery* interface. The transport of oxygen (from external air) in the porous carbon ...

### Gecko Foot

In nature, geckos use dry adhesion forces to climb walls. They have inspired researchers to develop synthetic gecko foot hairs to be used in, for example, robot applications. This model contains the nano/micro hierarchy of a synthetic gecko foot hair, where cantilever beams both in nano and micro scales describe the seta and spatula parts of one spatula stalk attached to a gecko foot. The ...

731–740 of 978