Direct numerical simulation results of aeolian tones generated by a two-dimensional obstacle (circular cylinder, square cylinder, NACA0012 airfoil) in a uniform flow are presented and the generation and propagation mechanisms of the sound are discussed. The unsteady compressible Navier-Stokes equations are solved by a highly-accurate finite difference scheme over the entire region from near to ...

We propose a novel information-theoretic approach for evaluating microphone arrays that relies on the array physics and geometry rather than the underlying beamforming algorithm. The analogy between Multiple-Input-Multiple-Output (MIMO) wireless communication channel and the acoustic channel of microphone arrays is exploited to define information measures of microphone arrays, which provide upp...

An innovative numerical prediction method of flow-induced noise is implemented to overcome the defect that traditional acoustic analogy cannot reflect interaction between turbulence vortex and sound. The classical cylindrical–airfoil interference model used perform simulation compared with experimental results. To start derivation Powell’s sound equation, an implicit three-dimensional fluid–aco...

Direct numerical simulations of a turbulent boundary layer over a bump were performed to examine the effects of surface longitudinal curvature on wall pressure fluctuations (pw) and flow induced noise. Turbulence statistics and frequency spectra were obtained to elucidate the response of wall pressure fluctuations to the longitudinal curvature and to the corresponding pressure gradient. Wall pr...

Analogy is a powerful boundary-transcending process that exploits a conceptual system's ability to perform controlled generalization in one domain and re-specialization into another. The result of this semantic leap is the transference of meaning from one concept to another from which metaphor derives its name (literally: to carry over). Such generalization and re-specialization can be achieved...

Abstract This paper constructs an iteration method based on Genetic Algorithm to optimize the acoustic filter structure comprising Helmholtz resonators, providing a new approach low-frequency filtering performance of under constraint keeping resonator volume unchanged. First, acoustic-electrical analogy is used design fifth-order Chebyshev type II structure, which comprises two rectangular reso...

The acoustic radiation from isotropic turbulence is computed numerically. A hybrid direct numerical simulation approach which combines direct numerical simulation (DNS) of the turbulent ow with the Lighthill acoustic analogy is utilized. It is demonstrated that the hybrid DNS method is a feasible approach to the computation of sound generated by turbulent ows. The acoustic e ciency in the simul...

We proposed an acoustic metamaterial with deep subwavelength thickness for low-frequency underwater sound absorption. The hybrid has a perforated facesheet, fluid-filled square honeycomb core inside rubber coating, and fixed backsheet. A theoretical model is established to predict the absorption performance of this based on theory micro-perforated panel electro-acoustic analogy. agrees well our...

In this work, an analytical study on the bending stiffnesses of corrugated board has been performed. Formulations to calculate the bending stiffnesses D11, D22, D12, and D66 of the equivalent plate representing the corrugated board have been established, and then compared to expressions suggested by other investigators. Several methods for modeling the shape of the corrugated orthotropic medium...

A LL jets have noise generation due to turbulent mixing; such mixing leads to the production of Reynolds stresses, the source term within the Lighthill acoustic analogy [1]. In addition to this source, a jet that possesses coherent, large-scale structures that travel with velocities exceeding the local speed of sound will emit Mach wave radiation, a highly efficient noise production mechanism. ...