# 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.

### Frequency Domain Modeling of a Capacitor

A capacitor with an applied sinusoidally time-varying voltage difference is modeled. A wide frequency range is considered and the impedance of the device is computed. Solver accuracy is addressed. The relationship between the frequency domain impedance and the steady-state capacitance and resistance of the device is discussed.

### Multi-Turn Coil Above an Asymmetric Conductor Plate

This model solves the Testing Electromagnetic Analysis Methods (TEAM) problem 7, “Asymmetrical Conductor with a Hole”—a benchmark problem concerning the calculation of eddy currents and magnetic fields produced when an aluminum conductor is placed asymmetrically above a multi-turn coil carrying a sinusoidally varying current. The simulation results at specified positions in space are compared ...

### Integrated Square-Shaped Spiral Inductor

This model considers a square inductor that is used for LC bandpass filters in MEMS systems. The simulation calculates the self-inductance. The first step in the modeling is to compute the currents in the inductor. These currents are the source for the magnetic flux computations, carried out in a second step.

### Magnetic Brake

A magnetic brake consists of a permanent magnet, which induces currents in a rotating copper disk. The resulting eddy currents interact with the magnetic flux to produce Lorentz forces and subsequently a braking torque. This 3D problem is solved using a stationary formulation for the electromagnetic field coupled to an ordinary differential equation for the rotational rigid body dynamics. ...

### Mutual Inductance and Induced Currents Between Single-Turn Coils

The mutual inductance between a primary and secondary single turn coil in a concentric coplanar arrangement is computed using a DC, steady-state, model and compared against the analytic solution. The induced currents in the secondary coil are computed using an AC, frequency-domain, analysis. The relationship between the AC induced currents and the DC inductance is discussed.

### Electromagnetic Plunger

This is a transient model of an electromagnetic plunger consisting of a magnetic core, nonmagnetic guider, multi-turn coil, and magnetic plunger attached to the spring and damper at the far end. The electromagnetic force on the plunger due to the transient current in the coil is calculated using the Maxwell stress tensor method in *Magnetic Fields* physics. The electromagnetic force is then ...

### Induction Motor in 2D

This is an example of a model of an induction motor in which the eddy currents are induced in the rotor by the time harmonic currents on the stator windings and the rotation of the rotor. In this example, we analyze the induction motor in 2D using the transient solver in the *Rotating Machinery, Magnetic* interface. We also investigate the motor’s start-up dynamics by coupling the ...

### An Electrodynamic Levitation Device

This model presents a solution to the Transient Electromagnetic Analysis Methods (TEAM) workshop problem 28, “An Electrodynamic Levitation Device”- a benchmark problem involving the dynamic coupling of electromagnetics and rigid body dynamics. An electrodynamic levitation force is produced by the induced eddy currents when a conductive disc is placed above two concentric coils carrying time ...

### Magnetic Lens

A scanning electron microscope samples images by scanning a target with a high-energy beam of electrons. The subsequent electron interactions produce signals such as secondary and back-scattered electrons that contain information about the sample surface topography. Electromagnetic lenses are used to focus this electron beam down to a spot about 10 nm wide on the sample surface. This model ...

### Eddy Currents in a Cylinder

The eddy currents in a conductive cylinder, generated from currents passing through a surrounding coil, are studied. The skin effect in the coil is also studied.

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