Investigation in Improving the Computational Accuracy of Local “Uncracked Stress” in Pipe-shaped Structure Using Isoparametric Boundary Element Method

1986 ◽  
pp. 681-688
Author(s):  
ZHANG YONGYUAN ◽  
LUO GANGMING ◽  
WU RONGHUA
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Computational Accuracy ◽  
Element Method

FAST MULTIPOLE BOUNDARY ELEMENT METHOD FOR LOW-FREQUENCY ACOUSTIC PROBLEMS BASED ON A VARIETY OF FORMULATIONS

2010 ◽  
Vol 18 (04) ◽  
pp. 363-395 ◽  
Author(s):  
YOSUKE YASUDA ◽  
TAKUYA OSHIMA ◽  
TETSUYA SAKUMA ◽  
ARIEF GUNAWAN ◽  
TAKAYUKI MASUMOTO
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Cell Structure ◽  
Low Frequency ◽  
Multipole Expansion ◽  
Diagonal Form ◽  
Fast Multipole ◽  
Computational Accuracy ◽  
Low Frequencies ◽  
Element Method

The fast multipole boundary element method (FMBEM), which is an efficient BEM that uses the fast multipole method (FMM), is known to suffer from instability at low frequencies when the well-known high-frequency diagonal form is employed. In the present paper, various formulations for a low-frequency FMBEM (LF-FMBEM), which is based on the original multipole expansion theory, are discussed; the LF-FMBEM can be used to prevent the low-frequency instability. Concrete computational procedures for singular, hypersingular, Burton-Miller, indirect (dual BEM), and mixed formulations are described in detail. The computational accuracy and efficiency of the LF-FMBEM are validated by performing numerical experiments and carrying out a formal estimation of the efficiency. Moreover, practically appropriate settings for numerical items such as truncation numbers for multipole/local expansion coefficients and the lowest level of the hierarchical cell structure used in the FMM are investigated; the differences in the efficiency of the LF-FMBEM when different types of formulations are used are also discussed.

Application of the Fast Multipole Boundary Element Method to Analysis of Sound Fields in Absorbing Materials

2009 ◽  
Author(s):  
Xiaobing Cui ◽  
Zhenlin Ji
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Large Scale ◽  
Computational Time ◽  
Fast Multipole ◽  
Computational Accuracy ◽  
Decomposition Approach ◽  
Sound Fields ◽  
Absorbing Material ◽  
Element Method

As an advanced boundary element method (BEM) employing the fast multipole algorithm, the fast multipole boundary element method (FMBEM) has been developed to realize fast computation and drastic memory saving for the large-scale problems. In the present study, The FMBEM is applied to analyze the interior sound fields that partially-filled with sound-absorbing material. The basic principle of FMBEM is introduced briefly, and the domain decomposition approach for FMBEM is investigated. The numerical errors in multipole expansions are analyzed in order to obtain the sufficient accuracy for the FMBEM computation of sound fields in sound-absorbing material. The sound pressures in a duct partially-filled with sound-absorbing material are calculated by using the present FMBEM and the conventional BEM, and then the computational accuracy and efficiency of FMBEM are discussed by comparing the results from the two methods. The numerical results showed that the FMBEM is capable to deal with the sound fields problems in sound-absorbing material, and can save computational time for the acoustic problems with large number of nodes.

A BOUNDARY-ELEMENT METHOD FOR ATOMIZATION OF A FINITE LIQUID JET

1995 ◽  
Vol 5 (6) ◽  
pp. 621-638 ◽  
Author(s):  
J. H. Hilbing ◽  
Stephen D. Heister ◽  
C. A. Spangler
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Liquid Jet ◽  
Element Method

Application of the Boundary Element Method and Modal Analysis to Tire Acoustics Problems

1993 ◽  
Vol 21 (2) ◽  
pp. 66-90 ◽  
Author(s):  
Y. Nakajima ◽  
Y. Inoue ◽  
H. Ogawa
Keyword(s):  
Finite Element ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Acoustic Radiation ◽  
Traffic Noise ◽  
Noise Prediction ◽  
Prediction System ◽  
Tire Noise ◽  
Acoustic Contribution ◽  
Element Method

Abstract Road traffic noise needs to be reduced, because traffic volume is increasing every year. The noise generated from a tire is becoming one of the dominant sources in the total traffic noise because the engine noise is constantly being reduced by the vehicle manufacturers. Although the acoustic intensity measurement technology has been enhanced by the recent developments in digital measurement techniques, repetitive measurements are necessary to find effective ways for noise control. Hence, a simulation method to predict generated noise is required to replace the time-consuming experiments. The boundary element method (BEM) is applied to predict the acoustic radiation caused by the vibration of a tire sidewall and a tire noise prediction system is developed. The BEM requires the geometry and the modal characteristics of a tire which are provided by an experiment or the finite element method (FEM). Since the finite element procedure is applied to the prediction of modal characteristics in a tire noise prediction system, the acoustic pressure can be predicted without any measurements. Furthermore, the acoustic contribution analysis obtained from the post-processing of the predicted results is very helpful to know where and how the design change affects the acoustic radiation. The predictability of this system is verified by measurements and the acoustic contribution analysis is applied to tire noise control.

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