Eigenfrequency Studies

Both the linearized Euler and the linearized Navier-Stokes interfaces have the Eigenfrequency study as a predefined study type. It should be noted that this analysis type is not suited when a non-zero background mean flow is present. In this case, the current formulation of the equation system, being solved, becomes non-Hermitian. Mathematically this means that there are no discrete eigenvalues but only a continuous spectrum of eigenvalues. It can be very difficult to find the acoustic (physical) eigenvalues.