Assessment of methodologies for the solution of the Ffowcs Williams and Hawkings equation using LES of incompressible single-phase flow around a finite-size square cylinder

Cianferra, Marta; Ianniello, S.; Armenio, Vincenzo

doi:10.1016/j.jsv.2019.04.001

Cited by 30 publications

(34 citation statements)

References 27 publications

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“…(2011) or Cianferra et al. (2019 a )). We have compared results obtained adopting both advective and non-advective formulations, finding the differences insignificant for the purpose of this study, although the classical FWH formulation appears more streamlined and easy to handle.…”

Section: Scaling Analysis Of the Fwh Equationmentioning

confidence: 99%

“…2011; Cianferra et al. 2019 a ). The presence of a uniform mean flow makes the numerical experiment herein considered comparable to a wind tunnel case.…”

Section: Scaling Analysis Of the Fwh Equationmentioning

confidence: 99%

“…Regarding the treatment of the time delays in the integrals above, we recall the maximum frequency parameter () introduced by Cianferra et al. (2019 a ). Once the microphone location and the integration domain of the FWH equation have been established, this parameter rules the maximum frequency that can be captured correctly, without calculating time delays.…”

Section: Scaling Analysis Of the Fwh Equationmentioning

confidence: 99%

“…We recall that, in order to avoid computation of the time delays, which makes unaffordable the direct evaluation of the volume terms (see Cianferra et al. 2019 a ), , with and the highest frequency at which the fluid-dynamic process is observed. Note that, if is the time step at which the fluid-dynamic data are stored, frequencies higher than are filtered out from the numerical solution.…”

Section: Scaling Analysis Of the Fwh Equationmentioning

confidence: 99%

“…The acoustic analogy has been successfully applied in a number of applications (Najafi-Yazdi, Bres & Mongeau 2011; Ianniello, Muscari & Di Mascio 2013; Wang & Wang 2013; Nitzkorski & Mahesh 2014; Jacob, Praveen & Mahesh 2018; Cianferra, Ianniello & Armenio 2019 a ). Among others, in Ianniello et al.…”

Section: Introductionmentioning

confidence: 99%

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Scaling properties of the Ffowcs-Williams and Hawkings equation for complex acoustic source close to a free surface

Cianferra

Armenio

2021

J. Fluid Mech.

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We perform a scaling analysis of the terms composing the Ffowcs-Williams and Hawkings (FWH) equation, which rules the propagation of noise generated by a rigid body in motion. Our analysis extends the seminal work of Lighthill (Proc. R. Soc. Lond. A, vol. 211, 1952, pp. 564–587) and the dimensional analysis of classical sources (monopole, dipole and quadrupole) considering all the FWH integral terms. Scaling properties are analysed in light of perfect/imperfect similarity when laboratory-scale data are used for full-scale predictions. As a test case we consider a hydrodynamic example, namely a laboratory-scale ship propeller. The data, obtained numerically in a previous study, were post-processed according to the scaling analysis presented herein. We properly scale the speed of sound to obtain perfect similarity and quantify the error with respect to the imperfect scaling. Imperfect similarity introduces errors in the acoustic response related both to the linear terms and to the nonlinear terms, the latter of great importance when the wake is characterized by robust and organized vorticity. Successively, we analyse the effect of a free surface, often present in hydrodynamic applications. We apply the method of images to the FWH equation. The free surface may generate a frequency-dependent constructive/destructive interference. The analysis of an archetypal acoustic field (monopole) provides robust explanation of these interference effects. Finally, we find that imperfect similarity and the absence of a free surface may introduce errors when model-scale data are used to obtain the full-scale acoustic pressure. The error is small for microphones placed in the near field and becomes relevant in the far field because of the nonlinear terms.

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Section: Scaling Analysis Of the Fwh Equationmentioning

confidence: 99%

“…2011; Cianferra et al. 2019 a ). The presence of a uniform mean flow makes the numerical experiment herein considered comparable to a wind tunnel case.…”

Section: Scaling Analysis Of the Fwh Equationmentioning

confidence: 99%

Section: Scaling Analysis Of the Fwh Equationmentioning

confidence: 99%

Section: Scaling Analysis Of the Fwh Equationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Scaling properties of the Ffowcs-Williams and Hawkings equation for complex acoustic source close to a free surface

Cianferra

Armenio

2021

J. Fluid Mech.

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An investigation on hydro-acoustic characteristics of submerged bodies with different geometric parameters

Bulut

Ergin

2022

Continuum Mech. Thermodyn.

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Numerical analyses and acoustic experiments were performed to investigate the effects of geometric parameters on the hydro-acoustic characteristics of flow over cylinders with circular, square and rectangular cross sections, respectively. A hybrid method which combines RANS and FWH equations was applied for the numerical analyses. The hydro-acoustic characteristics were obtained for circular cylinders with diameters, D = 9.5, 19.0, 38.0 and 65.0 mm, respectively, and aspect ratios, L/D = 2.5, 5.0 and 10.0. The effects of side-ratio, B/H , on the hydro-acoustic characteristics were investigated for cylinders with rectangular cross sections, for B/H = 0.3, 0.6, 1.0, 1.8 and 3.0, respectively. The range of Reynolds numbers considered for the numerical analyses and experiments is in the range of 2.25 × 10 4 and 1.7 × 10 5 . It was observed that the hydro-acoustic characteristics are greatly affected by the shear layer separation, reattachment mechanism and intensity disturbances. The noise spectrum strongly depends on the cross-sectional geometry of cylinder. An increase in the side ratio causes the spectrum to be narrower, and the main peak frequency increases with reducing side ratio. At constant Reynolds numbers, the broadband noise level and maximum sound pressure level decrease with decreasing aspect ratio, L/D, for cylinders with circular cross section. Moreover, the main peak frequency decreases with increasing diameter, whereas aspect ratio has no effect. The increase in diameter results in a decrease in the broadband noise level and the maximum sound pressure level. The numerical predictions were compared with experimental measurements, and a good agreement was found between the results.Underwater noise from submerged bodies is becoming a concern as a pollutant receiving considerable attention. Environmental noise pollution and its negative impacts on marine mammals are some of the critical issues resulted from high noise levels. In a turbulent flow, boundary-layer pressure fluctuations result in both hydrodynamic noise and flow-induced structural noise. The structural noise induced by flow is generated by eddies in turbulent flow exciting the body surface into flexural vibration. Particularly, dynamic interaction between structures and their surrounding fluid media is of great concern in flow-induced structural noise problems [1-3].

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Effects of Temperature, Salinity, and Fluid Type on Acoustic Characteristics of Turbulent Flow Around Circular Cylinder

Bulut

Ergin

2021

J. Marine. Sci. Appl.

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Assessment of methodologies for the solution of the Ffowcs Williams and Hawkings equation using LES of incompressible single-phase flow around a finite-size square cylinder

Abstract: Please cite this article as: M. Cianferra, S. Ianniello, V. Armenio, Assessment of methodologies for the solution of the Ffowcs Williams and Hawkings equation using LES of incompressible single-phase flow around a finite-size square cylinder,

Cited by 30 publications

References 27 publications

Scaling properties of the Ffowcs-Williams and Hawkings equation for complex acoustic source close to a free surface

Scaling properties of the Ffowcs-Williams and Hawkings equation for complex acoustic source close to a free surface

An investigation on hydro-acoustic characteristics of submerged bodies with different geometric parameters

Effects of Temperature, Salinity, and Fluid Type on Acoustic Characteristics of Turbulent Flow Around Circular Cylinder

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