Adaptive Integration Method Based on Sub-Division Technique for Nearly Singular Integrals in Near-Field Acoustics Boundary Element Analysis

Qu, Shiliang; Chen, Haoran; Li, Sheng

doi:10.1260/0263-0923.33.1.27

Cited by 5 publications

(5 citation statements)

References 47 publications

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“…Generally, b is the smallest dimension chosen out of length l and width b of the rectangular structure. At the cutoff squeeze number, r cutoff , damping and spring forces become equal, if only one term is taken in the summation of equations (32) and (33), then the cutoff squeeze number is approximated by…”

Section: -ðà1þmentioning

confidence: 99%

“…Moreover, the output of interest from the analysis is the damping force on the movable shuttle, and the boundary element method (BEM) is more accurate since the traction field exerted by fluid in the MEMS surface is a direct unknown of the numerical formulation. Qu et al 33 studied an efficient adaptive integration technique to perform near-field acoustics boundary element analysis. Unfortunately, standard BEM techniques 34,35 are ill conditioned and fail when applied to complex structure.…”

Section: Introductionmentioning

confidence: 99%

“…Qu et al. 33 studied an efficient adaptive integration technique to perform near-field acoustics boundary element analysis. Unfortunately, standard BEM techniques 34,35 are ill conditioned and fail when applied to complex structure.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The oscillating and electrostatic characteristics of microelectromechanical system cantilever structure analyzed based on the air gap domain

Jian

Zhang

et al. 2018

Journal of Low Frequency Noise, Vibration and Active Control

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Extensive modeling and simulation of the damping phenomenon, electrostatic actuation, and structural vibration analysis are performed. The governing partial differential equations of cantilever plate are obtained, and the resonant frequencies are calculated from the equilibrium equations. The damping forces of squeeze film are analyzed by obtaining the damping ratio and spring constant. Electrostatic actuation is applied to oscillate the cantilever to ensure that the displacement of the plate is above the thermal noise floor. Electrostatic actuating forces, displacement, and capacitance are calculated both numerically and analytically from the Poisson's equations. Squeeze film damping effects naturally occur if structures are subjected to loading situations such that a very thin film of fluid is trapped within structural joints, interfaces, etc. An accurate estimate of squeeze film effects is important to predict the performance of dynamic structures. Squeeze film effects are simulated by the finite element method. The accuracy of the compact model is studied by comparing its response to the numerical results calculated with the finite element method. The agreement is very good in a wide frequency band. The numerical study and the compact model are directly applicable in predicting the damping force and damping factors of squeeze film.

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Section: -ðà1þmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The oscillating and electrostatic characteristics of microelectromechanical system cantilever structure analyzed based on the air gap domain

Jian

Zhang

et al. 2018

Journal of Low Frequency Noise, Vibration and Active Control

View full text Add to dashboard Cite

show abstract

“…The latter is known as the hybrid method, which solves the flow field and acoustic field with different methods. Usually, traditional computational fluid dynamics (CFD) methods including DNS, LES/DES (detached eddy simulation), and Reynolds-averaged Navier-Stokes (RANS) equation methods are utilized to solve flow field and obtain sound sources while boundary element method (BEM), [11][12][13][14] acoustic analogy method 15 , and the Ffowcs Williams-Hawkings (FW-H) equation are employed for the acoustic generation and propagation. In comparison with direct simulation, the hybrid method is preferred to simulate aerodynamic noise of high-speed train due to relatively low requirements of computational configuration and resources.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic noise radiating from the inter-coach windshield region of a high-speed train

Dai

Zheng

Zhou

et al. 2018

Journal of Low Frequency Noise, Vibration and Active Control

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The aerodynamic noise has been the dominant factor of noise issues in high-speed train as the traveling speed increases. The inter-coach windshield region is considered as one of the main aerodynamic noise sources; however, the corresponding characteristics have not been well investigated. In this paper, a hybrid method is adopted to study the aerodynamic noise around the windshield region. The effectiveness of simulation methods is validated by a simple case of cavity noise. After that, the Reynolds-averaged Navier-Stokes simulation is used to obtain the characteristics of flow field around the windshield region, which determine the aerodynamic noise. Then the nonlinear acoustic solver approach is employed to acquire the near-field noise, while the Ffowcs-Williams/Hawking equation is solved for farfield acoustic propagation. The results indicate that the windshield region is approximately an open cavity filled with severe disturbance flow. According to the analysis of sound pressure distribution in the near-acoustic field, both sides of the windshield region appear symmetrical two-lobe shape with different directivities. The results of frequency spectrum analysis indicate that the aerodynamic noise inside inter-coach space is a typical broadband one from 100 Hz to 5k Hz, and most acoustic power is restricted in the low-medium frequency range (below 500 Hz). In addition, the acoustic power in the low frequency range (below 100 Hz) is closely related to the cavity resonance with the resonance peak frequency of 42 Hz. The overall sound pressure level at different speeds shows that the acoustic power grows approximately 5th power of the train speed. Two forms of outside-windshields are designed to reduce the noise around the windshield region, and the results show the full-windshield form is better in noise reduction, which apparently eliminates interior cavity noise of inter-coach space and lessens the overall sound pressure level on the sides of near-field by about 13 dB.

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“…20 In addition, relatively small dimensions limit the accuracy of these methods for low-frequency sound transmission calculation. Another common and effective simulation method that is widely used is the numerical simulation method, which includes the boundary element method (BEM), 21–24 finite element method, 25–28 and finite difference method. 29,30 In this method, reflection and diffraction are not considered separately but appear as an integral part of the solution of the wave equation.…”

Section: Introductionmentioning

confidence: 99%

Sound field study of a building near a roadway via the boundary element method

Wang

Cai

Zhong

et al. 2017

Journal of Low Frequency Noise, Vibration and Active Control

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A two-dimensional boundary element method with a constant element type was adopted to study the sound field of a building near a roadway. First, a factor analysis of the computed results has been done, which include the element length, the Hankel functions’ calculation accuracy, and numerical integration accuracy. Then, boundary element method is applied to calculate building attenuation with different building aspect ratios and different frequencies with balconies, followed by drawing of the sound field distribution diagram. The calculation results revealed the following: (1) a wider building results in a more severe sound attenuation; (2) balconies on different floors produce a reduction of approximately 15 dB for broadband spectral characteristics of A-weight road traffic noise, and the maximum values appear at the bottoms of balconies; (3) for the points in the balconies, higher sound frequencies are correlated to larger insertion loss, with the insertion loss increasing from 3 dB to >10 dB when the sound frequency increases from 20 to 4000 Hz; (4) calculations of three typical frequencies indicate that the insertion loss of 500 Hz (main frequency of heavy vehicles) is 6 dB less than that of 800 Hz (main frequency of light vehicles), i.e. the flow control of heavy vehicles could conspicuously improve the ambient acoustic environment of buildings near a roadway.

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Adaptive Integration Method Based on Sub-Division Technique for Nearly Singular Integrals in Near-Field Acoustics Boundary Element Analysis

Cited by 5 publications

References 47 publications

The oscillating and electrostatic characteristics of microelectromechanical system cantilever structure analyzed based on the air gap domain

The oscillating and electrostatic characteristics of microelectromechanical system cantilever structure analyzed based on the air gap domain

Aerodynamic noise radiating from the inter-coach windshield region of a high-speed train

Sound field study of a building near a roadway via the boundary element method

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