Selecting a Study Type
When variations in time are present there are two main approaches to how to represent the time dependence. The most straightforward is to solve the problem in the time domain by calculating the changes in the solution for each time step. This approach can be time consuming if small time steps are necessary for the desired accuracy. It is necessary to use this approach when the inputs are transients like turn-on and turn-off sequences.
An efficient simplification is to assume that all variations in time occur as sinusoidal signals. Then the problem is time-harmonic and it can formulated as a stationary problem in the frequency domain with complex-valued solutions. The complex value represents both the amplitude and the phase of the field, while the frequency is specified as a predefined scalar input or for frequency sweeps, provided as a solver parameter. This approach is useful because, combined with Fourier analysis, it applies to all periodic signals with the exception of nonlinear problems. Examples of typical frequency domain simulations are quasi-static problems where the input variables are sinusoidal signals.
For nonlinear problems, use a frequency domain study after a linearization of the problem, which assumes that the distortion of the sinusoidal signal is small.
Specify a Time Dependent study when you think that the nonlinear influence is very strong, or if you are interested in the harmonic distortion of a sinusoidal signal. It might also be more efficient to use a Time Dependent study if there is a periodic input with many harmonics, like a square-shaped signal.
There are some special predefined study types for the Induction Heating interface. This physics interface is based on the assumption that the magnetic cycle time is short compared to the thermal time scale (adiabatic assumption). Thus, it is associated with four predefined study sequences.
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Frequency-Stationary
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Time-harmonic magnetic fields
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Stationary heat transfer
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Frequency-Transient
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Time-harmonic magnetic fields
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Transient heat transfer
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Sequential Frequency-Stationary
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Time-harmonic magnetic fields
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Stationary heat transfer
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Sequential Frequency-Transient
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Time-harmonic magnetic fields
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Transient heat transfer