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.

### Transient Modeling of a Capacitor in a Circuit

A transient model of a capacitor is solved in combination with an external electrical circuit. The finite element model of the capacitor is combined with a circuit model of a voltage source and a resistor. A step change in voltage is applied, and the transient current through the capacitor is computed and compared to the analytic result.

### Generator in 2D

In this model, a rotor with permanent magnets and a nonlinear magnetic material rotates within a stator of the same magnetic material. The generated voltage in windings around the stator is calculated as a function of time. COMSOL Multiphysics models the rotation with assemblies and identity pairs. The nonlinearity of the magnetic material is also taken into account using an interpolation ...

### Modeling of an Electric Generator in 3D

These models demonstrate how to setup a sector model of rotating machinery both in 2D and 3D using *Rotating Machinery, Magnetic* interface in COMSOL Multiphysics. The stator in these permanent magnet ac generator examples consists of stator winding backed by iron core. The rotor includes the permanent magnets and iron core. The 2D and 3D model of the generator are included here. In 2D, the ...

### 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.

### Electromagnetic Forces on Parallel Current-Carrying Wires

This model shows a setup of two parallel wires with a constant current running through both. Their cross-sections are successively reduced until a set force per unit length is reached.

### 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 ...

### Computing the Resistance of a Wire

Every electrical device has some resistance. That is, when a voltage difference is applied across any two terminals of the device, there will be a directly proportional current flow. This model demonstrates how to compute the resistance of a short section of copper wire. The convergence of the solution with respect to the mesh size is also studied.

### 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. ...

### Inductive Heating of Copper Cylinder

The induced currents in a copper cylinder produce heat that in turn change the electrical conductivity. This means that the field propagation has to be solved simultaneously with the heat transfer through the cylinder and surrounding system. This model shows this coupling between eddy currents and heat transfer as a tutorial example.

### Induction Currents from Circular Coils

A time-varying current induces a time-varying magnetic field. The magnetic field induces currents in neighboring conductors. The induced currents are called eddy currents. In this model, the phenomenon is illustrated by a time-harmonic field simulation as well as a transient analysis, where the eddy currents resulting from the source being switched on are studied. Two current-carrying coils ...