# モデル・ギャラリー

The Model Gallery features COMSOL Multiphysics model files from a wide variety of application areas including the electrical, mechanical, fluid, and chemical disciplines. You can download ready-to-use models and step-by-step instructions for building the model, and use these as a starting point for your own modeling work. Use the Quick Search to find models relevant to your area of expertise, and login or create a COMSOL Access account that is associated with a valid COMSOL license to download the model files.

### Magnet Falling through Copper Tube

A cylindrical magnet falling through a copper tube induces eddy currents on the tube walls, which in turn, create a magnetic field that opposes the magnetic field of the magnet and induces a braking force that opposes the motion of the magnet. This model computes the velocity of the magnet after it is dropped, as it reaches its terminal velocity at which the magnetic braking force equals the ...

### Mutual Inductance and Induced Currents in a Multi-Turn Coil

The mutual inductance and induced currents between a single turn primary and twenty turn secondary coil in a concentric coplanar arrangement is computed using a frequency domain model. The secondary coil is modeled using a homogenized approach which does not explicitly consider each turn of the coil. The results are compared against analytic predictions.

### Eddy Currents in a Cylinder

An AC coil surrounding a metal cylinder induces eddy currents in the cylinder. The driving current in the coil can be specified in two ways: either as an external current density or as equivalent surface currents. In the first case, the skin effect can be studied by giving the coil a non-zero conductivity.

### Inductive Heating of a 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.

### Electric Machinery in 3D

This is a tutorial how to set up electric machinery in 3D using a combination of the magnetic fields and magnetic fields no currents interfaces.

### Red Blood Cell Separation using Magnetophoresis

Particle Tracing is used in conjunction with magnetic fields and pressure-driven microfluidic flow to calculate the separation of red blood cells from blood plasma using magnetophoresis. An array of soft iron rectangles on either side of a microfluidics channel modifies the magnetic field induced by a pair of neodymium permanent magnets. The resulting strong gradients in the magnetic field ...

### 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.

### Simulation of a 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. ...

### 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 ...

### 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.