Frequency Domain, Modal and Adaptive Frequency Sweep (AWE)
When solving models in the frequency domain and performing a large frequency sweep, it can sometimes be useful to use the Frequency Domain, Modal study or the Adaptive Frequency Sweep study steps. Both approaches can significantly speed up the solution time when sweeping over many frequencies.
For the Frequency Domain, Modal consider:
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The modal solver requires that the eigenfrequencies and modes can be easily found for up to twice the maximal study frequency. If a model contains many resonances in the desired frequency range, this may not be a good idea. It is often necessary to include the DC (static) pressure mode also to get the correct low frequency behavior.
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Note that since the modal solver assumes linear perturbation, all sources should be declared using the linper() operator.
For the Adaptive Frequency Sweep:
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This approach relies on the asymptotic waveform expansion or AWE approach. The Adaptive Frequency Sweep study is a special version of the regular Frequency Domain study.
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For this study add the AWE Expression feature to define the necessary AWE expression/metric for the solver.
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The AWE option can also be added under the Study Extensions section in a regular Frequency Domain study. In this case, it is necessary to enter an AWE expression manually. This is an expression that represents the response of the system. It needs to be a global expression. This can for example be the sound pressure level (SPL) evaluated using an integration or average operator. Integration in a point will give the SPL in that point.
Both solvers are used and discussed in the tutorial: Helmholtz Resonator Analyzed with Different Frequency Domain Solvers: Application Library path Acoustics_Module/Tutorials,_Pressure_Acoustics/helmholtz_resonator_solvers
See also the sections Frequency Domain Study and Frequency Domain, Modal and Time-Dependent, Modal Studies in the Study Types chapter.