This model shows how to combine an electric circuit simulation with a finite element simulation. The finite element model is an inductor with a nonlinear magnetic core and 1000 turns, where the number of turns is modeled using a distributed current technique. The circuit is imported into COMSOL Multiphysics as a SPICE netlist, which merges the inductor model and the circuit elements as ODEs.
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.
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.
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 ...
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.
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.
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.
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 ...
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.
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 ...