OPTIMISATION OF RAILWAY NOISE BARRIER DESIGN USING FINITE ELEMENTS AND BOUNDARY ELEMENT MODELLING METHODS

2021 ◽  
Author(s):  
C Bustos ◽  
V Jurdic ◽  
C Sharp ◽  
D Hiller
Keyword(s):  
Finite Elements ◽  
Boundary Element ◽  
Element Modelling ◽  
Railway Noise ◽  
Noise Barrier ◽  
Modelling Methods

Case study: Prediction and field tests of railway noise and effects of a low-height noise barrier

2020 ◽  
Vol 68 (4) ◽  
pp. 303-314
Author(s):  
Yuna Park ◽  
Hyo-In Koh ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
...  
Keyword(s):  
High Speed ◽  
Field Tests ◽  
Residential Areas ◽  
Railway Systems ◽  
Railway Noise ◽  
Sound Levels ◽  
Noise Barrier ◽  
The Difference ◽  
Reduction Effect ◽  
The Impact

Railway noise is calculated to predict the impact of new or reconstructed railway tracks on nearby residential areas. The results are used to prepare adequate counter- measures, and the calculation results are directly related to the cost of the action plans. The calculated values were used to produce noise maps for each area of inter- est. The Schall 03 2012 is one of the most frequently used methods for the production of noise maps. The latest version was released in 2012 and uses various input para- meters associated with the latest rail vehicles and track systems in Germany. This version has not been sufficiently used in South Korea, and there is a lack of standard guidelines and a precise manual for Korean railway systems. Thus, it is not clear what input parameters will match specific local cases. This study investigates the modeling procedure for Korean railway systems and the differences between calcu- lated railway sound levels and measured values obtained using the Schall 03 2012 model. Depending on the location of sound receivers, the difference between the cal- culated and measured values was within approximately 4 dB for various train types. In the case of high-speed trains, the value was approximately 7 dB. A noise-reducing measure was also modeled. The noise reduction effect of a low-height noise barrier system was predicted and evaluated for operating railway sites within the frame- work of a national research project in Korea. The comparison of calculated and measured values showed differences within 2.5 dB.

Application of the Complex Envelope Vectorization to a Boundary Element Formulation

2008 ◽  
Author(s):  
Oliviero Giannini ◽  
Aldo Sestieri
Keyword(s):  
Finite Elements ◽  
External Field ◽  
Boundary Element ◽  
High Frequency ◽  
Computational Cost ◽  
Field Variable ◽  
Element Formulation ◽  
Complex Envelope ◽  
Reduced Dimensions ◽  
Core Solution

The complex envelope vectorization (CEV) is a recent method that has been successfully applied to structural and internal acoustic problems. Unlike other methods proposed in the last two decades to solve high frequency problems, CEV is not an energy method, although it shares with all the other techniques a variable transformation of the field variable. By such transformation involving a Hilbert transform, CEV allows the representation of a fast oscillating signal through a set of low oscillating signals. Thanks to such transformation it is possible to solve a high frequency dynamic problem at a computational cost that is lower than that required by finite elements. In fact, by using finite elements, a high frequency problem usually implies large matrices. On the contrary the CEV formulation is obtained by solving a set of linear problems of highly reduced dimensions. Although it was proved that CEV is in general a successful procedure, it was shown that it is particularly appropriate when the modes of the system have a negligible role on the solution. Moreover, the numerical advantage of the CEV formulation is much more pronounced when full matrices are used. Thus, for the first time it is applied to a boundary element formulation (BEM). Both external and internal acoustic fields of increasing complexity are considered: the internal and external field generated by a pulsating sphere; the external field of a forced box, where the velocity field is determined by finite elements; a set of 4 plates that form an open cavity. The results are compared with those obtained by a BEM procedure (SYSNOISE), highlighting the good quality of the proposed approach. An estimate of the computational advantage is also provided. Finally it is worthwhile to point out that the reduction of the BE matrices allows for an in-core solution even for large problems.

scholarly journals Boundary element modelling of wave diffraction by interaction with wave-offshore structure and dredged region

2010 ◽  
Vol 17 (2) ◽  
pp. 67-71
Author(s):  
S. Kim ◽  
H. Lee
Keyword(s):  
Boundary Element ◽  
Wave Height ◽  
Wave Diffraction ◽  
Normal Incidence ◽  
Boundary Integral ◽  
Integral Approach ◽  
Front Face ◽  
Offshore Structure ◽  
Element Modelling ◽  
Sea Bed

Boundary element modelling of wave diffraction by interaction with wave-offshore structure and dredged region The purpose of this study is to estimate the wave height at the front face of breakwater (Refracted breakwater and Straight breakwater), when dredging like the submarine pit is performed in the distant offshore from outer breakwater. The wave field of the problem is considered to be two dimensional planes and the configuration of the pit region is designated by a single horizontal long-rectangular system. The numerical approach uses the Green function based on the boundary integral approach. The results of the present numerical works are illustrated by applying the normal and inclined incidence. It is shown that in the case of normal incidence, the ratio of wave height reduction at the front face of both types of breakwaters is approximately more than 20% due to the effect of the submarine pit on the sea bed. Furthermore, regardless of the type of breakwater and the difference in incident wave angles, the ratio of wave height was shown to be reduced.

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