Boundary Elements and other Mesh Reduction Methods XLII最新文献

ACOUSTIC SHAPE OPTIMIZATION BASED ON ISOGEOMETRIC BEM WITH ADJOINT VARIABLE METHOD 基于伴随变量法等几何边界的声形优化

Boundary Elements and other Mesh Reduction Methods XLII Pub Date : 2019-09-10 DOI: 10.2495/BE420041

Haibo Chen, Jie Wang, Changjun Zhen, Leilei Chen

引用次数: 0

FAST SINGULAR BOUNDARY METHOD: MATHEMATICAL BACKGROUND AND APPLICATION IN WAVE PROPAGATION ANALYSIS 快速奇异边界法:数学背景及其在波传播分析中的应用

Boundary Elements and other Mesh Reduction Methods XLII Pub Date : 2019-09-10 DOI: 10.2495/BE420161

Zhuojia Fu, Junpi Li, Qiang Xi

{"title":"FAST SINGULAR BOUNDARY METHOD: MATHEMATICAL BACKGROUND AND APPLICATION IN WAVE PROPAGATION ANALYSIS","authors":"Zhuojia Fu, Junpi Li, Qiang Xi","doi":"10.2495/BE420161","DOIUrl":"https://doi.org/10.2495/BE420161","url":null,"abstract":"Despite active research of many decades, numerical solution of the large-scale exterior wave problems remains a great challenge. The finite element method (FEM) needs to be coupled with some effective special treatments for handling unbounded domains, which are often tricky and largely based on trial–error experiences. The boundary element method (BEM) appears attractive to exterior problems, because the fundamental solutions satisfy the governing equation and Sommerfeld radiation condition at infinity. However, the BEM encounters computationally expensive singular numerical integration of fundamental solutions. To avoid this troublesome issue, the method of fundamental solutions (MFS) distributes the source nodes on a fictitious boundary outside the physical domain and is meshless, integration-free, and highly accurate. However, the placement of fictitious boundary is still an open issue for complex-shaped boundary and multiply connected domain problems. Recently, an alternative meshless boundary collocation approach, singular boundary method (SBM), has been proposed to solve various wave propagation problems. The key issue of the SBM is to determine the accurate source intensity factors instead of the singularities of fundamental solutions at origin. Several techniques have been proposed and investigated. The SBM is mathematically simple, easy-to-program, meshless, and applies the concept of source intensity factors to eliminating the singularity of the fundamental solutions. The method avoids singular numerical integrals in the BEM and circumvents the troublesome placement of the fictitious boundary in the MFS. This paper first presents the mathematical background of the SBM, and then applies it to wave propagation analysis.","PeriodicalId":429597,"journal":{"name":"Boundary Elements and other Mesh Reduction Methods XLII","volume":"100 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131010959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

COUPLING OF THE FAST BOUNDARY-DOMAIN INTEGRAL METHOD WITH THE STOCHASTIC COLLOCATION METHOD FOR FLUID FLOW SIMULATIONS 流体流动模拟的快速边界域积分法与随机配点法的耦合

Boundary Elements and other Mesh Reduction Methods XLII Pub Date : 2019-09-10 DOI: 10.2495/BE420211

J. Ravnik, A. Šušnjara, J. Tibaut, D. Poljak, M. Cvetković

引用次数: 0

NUMERICAL COMPUTATION OF DOUBLE SURFACE INTEGRALS OVER TRIANGULAR CELLS FOR VORTEX SHEET INTENSITY RECONSTRUCTION ON BODY SURFACE IN 3D VORTEX METHODS 三维涡旋法体表涡片强度重建中三角元上的二重曲面积分的数值计算

Boundary Elements and other Mesh Reduction Methods XLII Pub Date : 2019-09-10 DOI: 10.2495/BE420051

I. Marchevsky, G. Shcheglov

{"title":"NUMERICAL COMPUTATION OF DOUBLE SURFACE INTEGRALS OVER TRIANGULAR CELLS FOR VORTEX SHEET INTENSITY RECONSTRUCTION ON BODY SURFACE IN 3D VORTEX METHODS","authors":"I. Marchevsky, G. Shcheglov","doi":"10.2495/BE420051","DOIUrl":"https://doi.org/10.2495/BE420051","url":null,"abstract":"In this paper, a new approach is developed for the computation of vortex sheet intensity in vortex methods for 3D flow simulation. The problem is reduced to a boundary integral equation of the second kind on the body surface with respect to an unknown vector variable. The proposed technique makes it possible to improve the accuracy significantly in comparison to the technique traditionally implemented in vortex methods. A Galerkin-type approach is used with piecewise-constant basis functions. The coefficients of the resulting algebraic system are expressed through double surface integrals, calculated over the mesh cells. A semi-analytic technique is developed for the integrals calculation; integration over one cell is carried out analytically, while at the integration over the other cell (having common edge or vertex with the first one), the integrand is singular. Analytic expressions are obtained for singular parts of integrands and for the results of their integration. The regular parts of the integrands are integrated numerically. The developed approach provides less than 0.1% error. The regularization technique is developed for a divergence-free vortex sheet reconstruction on the body surface. The developed approach works well on coarse and non-uniform surface meshes for complex-shaped bodies, which is important for engineering applications.","PeriodicalId":429597,"journal":{"name":"Boundary Elements and other Mesh Reduction Methods XLII","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127575412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

NUMERICAL ANALYSIS OF BURIED VIBRATION PROTECTION DEVICES USING THE METHOD OF FUNDAMENTAL SOLUTIONS 用基本解法对埋地防振装置进行数值分析

Boundary Elements and other Mesh Reduction Methods XLII Pub Date : 2019-09-10 DOI: 10.2495/BE420201

C. Albino, L. Godinho, D. Dias‐da‐Costa, P. Amado-Mendes

引用次数: 0

BEM–EDM COUPLED ANALYSIS OF MULTI-SCALE PROBLEMS 多尺度问题Bem-edm耦合分析

Boundary Elements and other Mesh Reduction Methods XLII Pub Date : 2019-09-10 DOI: 10.2495/BE420091

Yong-Tong Zheng, Xiaowei Gao, Hai‐Feng Peng

{"title":"BEM–EDM COUPLED ANALYSIS OF MULTI-SCALE PROBLEMS","authors":"Yong-Tong Zheng, Xiaowei Gao, Hai‐Feng Peng","doi":"10.2495/BE420091","DOIUrl":"https://doi.org/10.2495/BE420091","url":null,"abstract":"In this paper, the element differential method (EDM), a new numerical method proposed recently, is coupled with the boundary element method (BEM), a traditional numerical method, for solving general multi-scale heat conduction problems. The basic algebraic equations in BEM are formulated in terms of temperatures and heat fluxes, which are the same as those in EDM. So, when coupling these two methods, we do not need to transform the variables like the thermal loads into heat fluxes as done with the finite element method (FEM). The key task in the proposed coupled method is to use the temperature consistency condition and the flux equilibrium equation at interface nodes of the two methods to eliminate all BEM nodes except for those on the interfaces. The detailed elimination process is presented in this paper, which can result in the final system of equations without iteration. The coefficient matrix of the final coupled system is sparse, even though a small part is dense. The coupled method inherits the advantage of EDM in flexibility and computational efficiency and the advantage of BEM in the robustness of treating multi-scale problems. A numerical example is given to demonstrate the correctness of this coupled method.","PeriodicalId":429597,"journal":{"name":"Boundary Elements and other Mesh Reduction Methods XLII","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128441076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A 2.5D BEM-FEM USING A SPECTRAL APPROACH TO STUDY SCATTERED WAVES IN FLUID–SOLID INTERACTION PROBLEMS 用谱法研究流固相互作用问题中的散射波

Boundary Elements and other Mesh Reduction Methods XLII Pub Date : 2019-09-10 DOI: 10.2495/BE420101

F. J. Cruz-Muñoz, A. Romero, P. Galvín, A. Tadeu

引用次数: 0

BOUNDARY ELEMENT ANALYSIS OF THIN-WALLED STRUCTURES USING AN EXPANDING ELEMENT INTERPOLATION METHOD 薄壁结构的边界元扩展插值分析

Boundary Elements and other Mesh Reduction Methods XLII Pub Date : 2019-09-10 DOI: 10.2495/BE420031

Jianming Zhang, Y. Zhong, Le Yang, Baotao Chi, Chuanming Ju

引用次数: 0

SINGULAR BOUNDARY METHOD IN A FREE VIBRATION ANALYSIS OF COMPOUND LIQUID-FILLED SHELLS 复合充液壳体自由振动分析中的奇异边界法

Boundary Elements and other Mesh Reduction Methods XLII Pub Date : 2019-09-10 DOI: 10.2495/BE420171

V. Gnitko, Kyryl Degtyariov, Artem Karaiev, E. Strelnikova

引用次数: 10

FAST METHODS FOR VORTEX INFLUENCE COMPUTATION IN MESHLESS LAGRANGIAN VORTEX METHODS FOR 2D INCOMPRESSIBLE FLOWS SIMULATION 二维不可压缩流动无网格拉格朗日涡法中涡影响的快速计算方法

Boundary Elements and other Mesh Reduction Methods XLII Pub Date : 2019-09-10 DOI: 10.2495/BE420231

D. Leonova, I. Marchevsky, E. Ryatina

{"title":"FAST METHODS FOR VORTEX INFLUENCE COMPUTATION IN MESHLESS LAGRANGIAN VORTEX METHODS FOR 2D INCOMPRESSIBLE FLOWS SIMULATION","authors":"D. Leonova, I. Marchevsky, E. Ryatina","doi":"10.2495/BE420231","DOIUrl":"https://doi.org/10.2495/BE420231","url":null,"abstract":"Vortex methods are a powerful tool for solving engineering problems of incompressible flow simulation around airfoils. The vorticity is considered as a primary computed variable. According to the Navier–Stokes equations written down in Helmholtz-type form (for 2D case), new vorticity is generated only on the surface line of an airfoil. Its intensity is unknown and can be found from the solution of the boundary integral equation resulting from the no-slip boundary condition satisfaction. The right-hand side of the integral equation in the simplest case depends on the incident flow velocity and vorticity distribution in the flow domain. For the velocity field computation, it is necessary to take into account the influence of all the vortices, which simulate the vorticity distribution in the flow. These vortices are moving in the flow with velocities calculated as sums of point-to-point vortex influences, so the computation complexity of such operation is proportional to 2 N where N is the number of vortices. In practice, N can have the order of tens or hundreds of thousands, up to a million, so the application of the “direct” method for velocities calculation becomes impossible. In this paper, two fast methods having logarithmic (proportional to log N N ) computational complexity are implemented and investigated. The first method is an analogue of the Barnes–Hut fast method for the N-body problem. The second one is based on fast solution of the Poisson’s equation with respect to the stream function on rather coarse mesh by using the fast Fourier transform technique with some special procedure for the results correction. Numerical complexity estimations for both methods are derived. Their sequential and parallel implementations are developed. Numerical experiments show that the FFT-based method is more efficient. Total acceleration compared with the “direct” method is over 1000 times for 500,000 vortex elements.","PeriodicalId":429597,"journal":{"name":"Boundary Elements and other Mesh Reduction Methods XLII","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134028817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1