Comparison of three numerical methods for acoustic propagation in a lined duct with flow

Characterization and suppression of the hydrodynamic instability in the time domain for acoustic propagation in a lined flow duct

“…The GTS method is now applied to the GIT benchmark problem [58], which is widely used for validation of aeroacoustic solvers of lined ducts under plane wave propagation. A number of numerical studies have reported the existence of an instability at 1 kHz for this problem [16,59,28].…”

“…Detailed numerical analysis with a mass-spring-damper impedance model showed that the use of a mean velocity profile instead of the Ingard-Myers condition transformed the unstable mode from absolute to convective [27]. However, even with a full velocity profile, absolute instabilities seems to be present in time-domain simulations for liners with a more realistic broadband impedance [28].…”

Domain decomposition method based on One-Way approaches for sound propagation in a partially lined duct

“…The value of this coefficient will differ depending on whether a OWNS or OWE simulation is performed. This expression is taken from [33] where the third component along the z-axis has been removed, since the One-Way simulations are performed in 2-D. This expression of the Poiseuille flow presents a thinner boundary layer than the one taken in [33].…”

“…This expression is taken from [33] where the third component along the z-axis has been removed, since the One-Way simulations are performed in 2-D. This expression of the Poiseuille flow presents a thinner boundary layer than the one taken in [33]. In Figure 4, the baseflow profiles are plotted along the transverse direction with the experimental data taken in the center of the duct. )…”

Further assessment of a time domain impedance boundary condition for the numerical simulation of noise-absorbing materials

“…43 Second category relates to those models that are rather built upon a mathematical modelling of the material's noise attenuation characteristics themselves, i.e., its impedance. These models [44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61] are of mathematical nature and do not require any prior knowledge of the material characteristics, but rather an accurate description of its noise attenuation behaviourwhich, in turns, requires a proper experimental identification (namely eduction) of its impedance spectrum. Each class of models led to the emergence of numerous TDIBC formulations, each one distinguishing itself from the others by its intrinsic modelling and/or algorithmic implementation.…”