In this paper,we establish the exponential convergence theory for the multipole and local expansions,shifting and translation operators for the Green's function of 3-dimensional Laplace equation in layered media.A...In this paper,we establish the exponential convergence theory for the multipole and local expansions,shifting and translation operators for the Green's function of 3-dimensional Laplace equation in layered media.An immediate application of the theory is to ensure the exponential convergence of the FMM which has been shown by the numerical results reported in[27].As the Green's function in layered media consists of free space and reaction field components and the theory for the free space components is well known,this paper will focus on the analysis for the reaction components.We first prove that the density functions in the integral representations of the reaction components are analytic and bounded in the right half complex wave number plane.Then,by using the Cagniard-de Hoop transform and contour deformations,estimates for the remainder terms of the truncated expansions are given,and,as a result,the exponential convergence for the expansions and translation operators is proven.展开更多
It is shown that the basis of the ellipsoidal acoustic infinite elementBurnett method, the multipole expansion, cannot represent real ellipsoidal acoustic field exactly.To solve the problem, a weight of angular direct...It is shown that the basis of the ellipsoidal acoustic infinite elementBurnett method, the multipole expansion, cannot represent real ellipsoidal acoustic field exactly.To solve the problem, a weight of angular direction is added to the multipole expansion. Thecomparison of the modified method and the prime method shows that the modified method can describeand solve the ellipsoidal acoustic field more accurately than ever. A dilating sphere is used totest the new method further. Unlike other infinite element methods, varied ratio of the ellipsoidalartificial boundary instead of sphere is used. The pressure value of the artificial boundary isutilized as the initial value of the new method. Then the radiating phenomena of the ellipsoidalacoustic field can be researched using the new method. These examples show the feasibility of theadaptive method.展开更多
The fast multipole method (FMM) has been used to reduce the computing operations and mem- ory requirements in large numerical analysis problems. In this paper, the FMM based on Taylor expansions is combined with the...The fast multipole method (FMM) has been used to reduce the computing operations and mem- ory requirements in large numerical analysis problems. In this paper, the FMM based on Taylor expansions is combined with the boundary element method (BEM) for three-dimensional elastostatic problems to solve thin plate and shell structures. The fast multipole boundary element method (FM-BEM) requires O(N) opera- tions and memory for problems with N unknowns. The numerical results indicate that for the analysis of thin structures, the FM-BEM is much more efficient than the conventional BEM and the accuracy achieved is sufficient for engineering applications.展开更多
基金supported by the US National Science Foundation (Grant No.DMS-1950471)the US Army Research Office (Grant No.W911NF-17-1-0368)partially supported by NSFC (grant Nos.12201603 and 12022104)。
文摘In this paper,we establish the exponential convergence theory for the multipole and local expansions,shifting and translation operators for the Green's function of 3-dimensional Laplace equation in layered media.An immediate application of the theory is to ensure the exponential convergence of the FMM which has been shown by the numerical results reported in[27].As the Green's function in layered media consists of free space and reaction field components and the theory for the free space components is well known,this paper will focus on the analysis for the reaction components.We first prove that the density functions in the integral representations of the reaction components are analytic and bounded in the right half complex wave number plane.Then,by using the Cagniard-de Hoop transform and contour deformations,estimates for the remainder terms of the truncated expansions are given,and,as a result,the exponential convergence for the expansions and translation operators is proven.
文摘It is shown that the basis of the ellipsoidal acoustic infinite elementBurnett method, the multipole expansion, cannot represent real ellipsoidal acoustic field exactly.To solve the problem, a weight of angular direction is added to the multipole expansion. Thecomparison of the modified method and the prime method shows that the modified method can describeand solve the ellipsoidal acoustic field more accurately than ever. A dilating sphere is used totest the new method further. Unlike other infinite element methods, varied ratio of the ellipsoidalartificial boundary instead of sphere is used. The pressure value of the artificial boundary isutilized as the initial value of the new method. Then the radiating phenomena of the ellipsoidalacoustic field can be researched using the new method. These examples show the feasibility of theadaptive method.
基金Supported by the National Natural Science Foundation of China (No. 10172053)
文摘The fast multipole method (FMM) has been used to reduce the computing operations and mem- ory requirements in large numerical analysis problems. In this paper, the FMM based on Taylor expansions is combined with the boundary element method (BEM) for three-dimensional elastostatic problems to solve thin plate and shell structures. The fast multipole boundary element method (FM-BEM) requires O(N) opera- tions and memory for problems with N unknowns. The numerical results indicate that for the analysis of thin structures, the FM-BEM is much more efficient than the conventional BEM and the accuracy achieved is sufficient for engineering applications.
