Direct Evaluation of Acoustic-Intensity Vector Field Around an Impedance Scattering Body

Vector Aeroacoustics for a Uniform Mean Flow: Acoustic Intensity and Acoustic Power

“…Based on the acoustic pressure and acoustic velocity integral formulations suitable for uniform mean flow, this paper developed a numerical method to compute and visualize the acoustic intensity field around stationary and rotating sources in a uniform mean flow, which is an extension of the recently developed vector aeroacoustics method with an assumption of quiescent acoustic medium [5,7]. Moreover, the acoustic power output from the monopole and dipole sources in the uniform mean flow was studied analytically and numerically.…”

“…Moreover, visualizing the acoustic intensity field can reveal the detailed propagation path of the acoustic energy and the mechanism of sound propagation, thus it is beneficial to achieve an optimal noise reduction efficacy by optimizing the shape and installation location of the acoustic liner. For examples, visualization of acoustic intensity fields illustrates three modes of acoustic energy output from rotating sources [5], reveals the effect of scattering surfaces on the redistribution of the acoustic energy [6] and displays the primary acoustic-absorbing position around an impedance scattering surface [7]. All the above studies were carried out with an assumption of quiescent acoustic medium, and in this paper, the acoustic intensity field around sources as well as the acoustic power output in a uniform mean flow are investigated.…”

Improved Equivalent Source Method to Predict Sound Scattered by Solid Surfaces

“…The former is calculated directly with the method of Green's function in free space, and the latter can be solved by using either the BEM or the ESM. Details on the time-domain and frequency-domain ESMs can be found in recent references [1,2,[12][13][14], here we only present the main computational steps of the frequencydomain ESM.…”

“…Either monopole sources or dipole sources can be used to represent the equivalent sources. Here, only the equivalent monopole sources are used for the sake of simplicity description, and the introduction on the equivalent dipole sources can be found in [14]. Therefore, the following equations are used to establish the acoustic response of the n th observer to the m th equivalent source.…”

Vector Aeroacoustics for Uniform Mean Flow: Acoustic Velocity and Vortical Velocity

“…Ghorbaniasl et al [19] developed time-domain acoustic velocity formulations for monopole and dipole sources in arbitrary motion, and Mao et al [20] deduced frequency-domain acoustic velocity formulations for rotating monopole and dipole sources with a constant angular speed. After that, acoustic intensity fields around sources [21] and scattering boundaries [22,23] were visualized to illustrate the propagation of acoustic energy. All the above-mentioned investigations on the vector aeroacoustics method assume that acoustic medium is quiescent.…”