Hypersingular Boundary Integral Equations: Some Applications in Acoustic and Elastic Wave Scattering

1990 ◽  
Vol 57 (2) ◽  
pp. 404-414 ◽  
Author(s):  
G. Krishnasamy ◽  
L. W. Schmerr ◽  
T. J. Rudolphi ◽  
F. J. Rizzo
Keyword(s):  
Boundary Integral Equations ◽  
Acoustic Scattering ◽  
Boundary Integral ◽  
Three Dimensions ◽  
Finite Part ◽  
Important Special Case ◽  
Hypersingular Integrals ◽  
Hadamard Finite Part ◽  
Spatial Dimensions ◽  
Regular Line

The properties of hypersingular integrals, which arise when the gradient of conventional boundary integrals is taken, are discussed. Interpretation in terms of Hadamard finite-part integrals, even for integrals in three dimensions, is given, and this concept is compared with the Cauchy Principal Value, which, by itself, is insufficient to render meaning to the hypersingular integrals. It is shown that the finite-part integrals may be avoided, if desired, by conversion to regular line and surface integrals through a novel use of Stokes’ theorem. Motivation for this work is given in the context of scattering of time-harmonic waves by cracks. Static crack analysis of linear elastic fracture mechanics is included as an important special case in the zero-frequency limit. A numerical example is given for the problem of acoustic scattering by a rigid screen in three spatial dimensions.

AUTOMATIC QUADRATURE SCHEME FOR EVALUATING HYPERSINGULAR INTEGRALS

2012 ◽  
Vol 09 ◽  
pp. 581-585
Author(s):  
SUZAN J. OBAIYS ◽  
Z. K. ESKHUVATOV ◽  
N. M. A. NIK LONG
Keyword(s):  
Numerical Experiments ◽  
Second Order ◽  
Close Connection ◽  
Finite Part ◽  
Smooth Functions ◽  
Hypersingular Integrals ◽  
Quadrature Scheme ◽  
Hadamard Finite Part ◽  
Automatic Quadrature

Hasegawa constructed the automatic quadrature scheme (AQS), of Cauchy principle value integrals for smooth functions. There is a close connection between Hadamard and Cauchy principle value integral. In this paper, we modify AQS for hypersingular integrals with second-order singularities, using hasegawa's formula and based on the relations between Hadamard finite part integral and Cauchy principle value integral. Numerical experiments are also given, to validate the modified AQS.

scholarly journals Regularization of the Divergent Integrals. II. Application in Fracture Mechanics.

2007 ◽  
Vol 4 (2) ◽  
Author(s):  
Vladimir Zozulya
Keyword(s):  
Fracture Mechanics ◽  
Integral Equations ◽  
Convex Polygon ◽  
Boundary Integral Equations ◽  
Boundary Integral ◽  
Hypersingular Integrals ◽  
Divergent Integral ◽  
Contour Integrals ◽  
Weakly Singular ◽  
Arbitrary Convex

In this article the methodology for divergent integral regularization developed in [8] is applied for regularization of the weakly singular and hypersingular integrals, which arise when the boundary integral equations (BIE) methods are used to solve problems in fracture mechanics. The approach is based on the theory of distribution and the application of the Green theorem. The weakly singular and hypersingular integrals over arbitrary convex polygon have been transformed to the regular contour integrals that can be easily calculated analytically or numerically.

scholarly journals Integro-differential equations with singular and hypersingular integrals

2019 ◽  
Vol 54 (4) ◽  
pp. 404-407 ◽  
Author(s):  
E. I. Zverovich ◽  
A. P. Shilin
Keyword(s):  
Differential Equations ◽  
Complex Plane ◽  
Singular Integrals ◽  
Closed Curve ◽  
Special Structure ◽  
Finite Part ◽  
Hypersingular Integrals ◽  
Hadamard Finite Part

Quadrature linear integro-differential equations on a closed curve located in the complex plane are solved. The equations contain singular integrals which are understood in the sense of the main value and hypersingular integrals which are understood in the sense of the Hadamard finite part. The coefficients of the equations have a special structure.

A Complex Variable Boundary Element-Free Method for Potential and Helmholtz Problems in Three Dimensions

2019 ◽  
Vol 17 (02) ◽  
pp. 1850129 ◽  
Author(s):  
Xiaolin Li ◽  
Shougui Zhang ◽  
Yan Wang ◽  
Hao Chen
Keyword(s):  
Boundary Element ◽  
Complex Variable ◽  
Boundary Integral Equations ◽  
Boundary Integral ◽  
Three Dimensions ◽  
Variable Boundary ◽  
Current Implementation ◽  
Element Free Method ◽  
Element Free ◽  
3D Surfaces

The complex variable boundary element-free method (CVBEFM) is a meshless method that takes the advantages of both boundary integral equations (BIEs) in dimension reduction and the complex variable moving least squares (CVMLS) approximation in element elimination. The CVBEFM is developed in this paper for solving 3D problems. This paper is an attempt in applying complex variable meshless methods to 3D problems. Formulations of the CVMLS approximation on 3D surfaces and the CVBEFM for 3D potential and Helmholtz problems are given. In the current implementation, the CVMLS shape function of 3D problems is formed with 1D basis functions, and the boundary conditions in the CVBEFM can be applied directly and easily. Some numerical examples are presented to demonstrate the method.

scholarly journals Magnetic micro-droplet in rotating field: numerical simulation and comparison with experiment

2017 ◽  
Vol 821 ◽  
pp. 266-295 ◽  
Author(s):  
J. Erdmanis ◽  
G. Kitenbergs ◽  
R. Perzynski ◽  
A. Cēbers
Keyword(s):  
Magnetic Field ◽  
Boundary Integral Equations ◽  
Three Dimensional ◽  
Dipolar Interaction ◽  
Boundary Integral ◽  
Rotating Magnetic Field ◽  
Three Dimensions ◽  
Triaxial Ellipsoid ◽  
Equilibrium Shapes ◽  
Magnetic Droplet

Magnetic droplets obtained by induced phase separation in a magnetic colloid show a large variety of shapes when exposed to an external field. However, the description of the shapes is often limited. Here, we formulate an algorithm based on three-dimensional boundary-integral equations for strongly magnetic droplets in a high-frequency rotating magnetic field, allowing us to find their figures of equilibrium in three dimensions. The algorithm is justified by a series of comparisons with known analytical results. We compare the calculated equilibrium shapes with experimental observations and find a good agreement. The main features of these observations are the oblate–prolate transition, the flattening of prolate shapes with the increase of magnetic field strength and the formation of starfish-like equilibrium shapes. We show both numerically and in experiments that the magnetic droplet behaviour may be described with a triaxial ellipsoid approximation. Directions for further research are mentioned, including the dipolar interaction contribution to the surface tension of the magnetic droplets, accounting for the large viscosity contrast between the magnetic droplet and the surrounding fluid.

scholarly journals A General Algorithm for the Numerical Solution of Hypersingular Boundary Integral Equations

1992 ◽  
Vol 59 (3) ◽  
pp. 604-614 ◽  
Author(s):  
M. Guiggiani ◽  
G. Krishnasamy ◽  
T. J. Rudolphi ◽  
F. J. Rizzo
Keyword(s):  
Integral Equations ◽  
Boundary Integral Equations ◽  
Collocation Point ◽  
Three Dimensional ◽  
Careful Analysis ◽  
Boundary Integral ◽  
Hypersingular Integrals ◽  
Closed Surfaces ◽  
First Time ◽  
General Method

The limiting process that leads to the formulation of hypersingular boundary integral equations is first discussed in detail. It is shown that boundary integral equations with hypersingular kernels are perfectly meaningful even at non-smooth boundary points, and that special interpretations of the integrals involved are not necessary. Careful analysis of the limiting process has also strong relevance for the development of an appropriate numerical algorithm. In the second part, a new general method for the evaluation of hypersingular surface integrals in the boundary element method (BEM) is presented. The proposed method can be systematically applied in any BEM analysis, either with open or closed surfaces, and with curved boundary elements of any kind and order (of course, provided the density function meets necessary regularity requirements at each collocation point). The algorithm operates in the parameter plane of intrinsic coordinates and allows any hypersingular integral in the BEM to be directly transformed into a sum of a double and a one-dimensional regular integrals. Since all singular integrations are performed analytically, standard quadrature formulae can be used. For the first time, numerical results are presented for hypersingular integrals on curved (distorted) elements for three-dimensional problems.

Fast direct solvers for integral equations in complex three-dimensional domains

Acta Numerica ◽  
2009 ◽  
Vol 18 ◽  
pp. 243-275 ◽  
Author(s):  
Leslie Greengard ◽  
Denis Gueyffier ◽  
Per-Gunnar Martinsson ◽  
Vladimir Rokhlin
Keyword(s):  
Integral Equations ◽  
Degrees Of Freedom ◽  
Boundary Integral Equations ◽  
Three Dimensional ◽  
Boundary Integral ◽  
Three Dimensions ◽  
Computer Hardware ◽  
Matrix Vector Multiplication ◽  
Gradient Type ◽  
Mathematical Foundations

Methods for the solution of boundary integral equations have changed significantly during the last two decades. This is due, in part, to improvements in computer hardware, but more importantly, to the development of fast algorithms which scale linearly or nearly linearly with the number of degrees of freedom required. These methods are typically iterative, based on coupling fast matrix-vector multiplication routines with conjugate-gradient-type schemes. Here, we discuss methods that are currently under development for the fast, direct solution of boundary integral equations in three dimensions. After reviewing the mathematical foundations of such schemes, we illustrate their performance with some numerical examples, and discuss the potential impact of the overall approach in a variety of settings.

scholarly journals Boundary Element Analysis of Anisotropic Thermomagnetoelectroelastic Solids with 3D Shell-Like Inclusions

2017 ◽  
Vol 11 (4) ◽  
pp. 308-312
Author(s):  
Iaroslav Pasternak ◽  
Heorhiy Sulym
Keyword(s):  
Boundary Element ◽  
Boundary Integral Equations ◽  
Boundary Integral ◽  
Element Analysis ◽  
Extended Body ◽  
Hypersingular Integrals ◽  
Polynomial Mappings ◽  
Square Root Singularity ◽  
Field Intensity Factors ◽  
Element Technique

AbstractThe paper presents novel boundary element technique for analysis of anisotropic thermomagnetoelectroelastic solids containing cracks and thin shell-like soft inclusions. Dual boundary integral equations of heat conduction and thermomagnetoelectroelasticity are derived, which do not contain volume integrals in the absence of distributed body heat and extended body forces. Models of 3D soft thermomagnetoelectroelastic thin inclusions are adopted. The issues on the boundary element solution of obtained equations are discussed. The efficient techniques for numerical evaluation of kernels and singular and hypersingular integrals are discussed. Nonlin-ear polynomial mappings are adopted for smoothing the integrand at the inclusion’s front, which is advantageous for accurate evaluation of field intensity factors. Special shape functions are introduced, which account for a square-root singularity of extended stress and heat flux at the inclusion’s front. Numerical example is presented.

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