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.

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Tunable Evanescent Mode Cavity Filter Using a Piezo Actuator

An evanescent mode cavity filter can be realized by adding a structure inside of the cavity. This structure changes the resonant frequency lower than the dominant mode of the unfilled cavity. A piezo actuator is used to control the size of a small air gap which provides the tunability of the resonant frequency.

Turbomolecular Pump

The *Free Molecular Flow* interface, available in the Molecular Flow Module, is an efficient tool for modeling extremely rarefied gases when the gas molecules move much faster than any geometric entities in the domain. For turbomolecular pumps, in which the blades move at speeds comparable to the thermal speed of the gas molecules, a Monte Carlo approach is needed. In this example, the ...

Fuel Cell Bipolar Plate

A fuel cell stack operates at temperatures just below 100 °C, which means that it has to be heated at start-up. The fuel cell stack consists of unit cell of anode, membrane, and cathode connected in series through bipolar plates. This study presents a model that couples the thermal and structural deformations in a fuel cell bipolar plate. The magnitude and position of the thermal stresses ...

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 ...

Rat-Race Coupler

A 180° Ring Hybrid (Rat-Race Coupler) is a four-port network with 180° phase difference between two ports. It is cheaper to manufacture this type of microstrip line component compared to a wave guide 180° hybrid junction, so called magic-T. The objective of this model is to compute the S-parameters and to observe the matching, isolation, and coupling around the operating frequency.

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 ...

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 ...

1D Lithium-Ion Battery Drive-Cycle Monitoring

This application shows how a battery cell exposed to a hybrid electric vehicle drive cycle can be investigated with the Lithium-Ion Battery interface in COMSOL. This model predicts the battery behavior to make comparisons of the monitored properties. They can be used to understand the battery's behavior during the cycle better, since the model includes can calculate more than is measurable, for ...

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 ...

Axial Homopolar Induction Bearing in 3D

This model illustrates the working principle of an axial homopolar induction bearing. An electrically conducting rotor rotating in a magnetic field produced by a permanent magnets induces eddy currents on the conducting rotor. The eddy currents, in turn, produce a magnetic field that opposes the magnetic fields by the magnets and induces a force that opposes the motion of the rotor. The axial ...