Time Dependent Study
The complete equations behind the theory of acoustic wave propagation are time dependent, as discussed in the Frequency Domain Study section. Solving time-domain equations is more complicated from a numerical point of view. They are necessary when studying systems where the time of flight is of importance, like in a flowmeter application. Short-term transient processes like step and impulse responses can benefit from modeling in the time domain, if not for efficiency so for convenience.
A dedicated Transient Solver Settings settings section exist at the physics level for all the transient acoustics interfaces where the Maximum frequency to resolve should be entered.
Some central modeling techniques, such as the use of PMLs, are not available for all physics with the Time Dependent study type. PMLs only exist in the time domain for the Pressure Acoustics, Time Domain interface. Be careful when defining your sources to avoid, as far as possible, exciting waves at frequencies that the mesh cannot resolve.
Time Dependent in the COMSOL Multiphysics Reference Manual.