摘要:

AbstractEulerian–Langrangian localized adjoint methods (ELLAM) were developed to solve convection–diffusion–reaction equations governing contaminant transport in groundwater flowing through a porous medium, subject to various combinations of boundary conditions. In this article, we prove optimal‐order error estimates and some superconvergence results for the ELLAM schemes. In contrast to many existing estimates for a variety of numerical methods, which often contain the temporal derivatives of the exact solution, our error estimates contain the total derivatives of the exact solution but do not involve any temporal derivatives of the exact solution. © 1995 John Wiley&S

ISSN:0749-159X    

DOI:10.1002/num.1690110103

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA finite difference scheme for the two‐dimensional, second‐order, nonlinear elliptic equation is developed. The difference scheme is derived using the local solution of the differential equation. A 13‐point stencil on a uniform mesh of sizehis used to derive the finite difference scheme, which has a truncation error of orderh4. Well‐known iterative methods can be employed to solve the resulting system of equations. Numerical results are presented to demonstrate the fourth‐order convergence of the scheme. © 1995 John Wiley

ISSN:0749-159X    

DOI:10.1002/num.1690110104

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractA computational method for a system of partial integrodifferential equations of Volterra type is developed. These equations describe the damping of pressure waves in tubes of circular form, taking into account the nonstationary increase of friction. The analytical solution of the model equations is given. A rapidly convergent expansion as well as sharp error estimates for the approximate solutions are obtained. Finally an efficient algorithm using recursion formulas is presented and the algorithm is compared numerically with the method of characteristics. © 1995 John Wiley&Sons, Inc

ISSN:0749-159X    

DOI:10.1002/num.1690110105

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThe Neumann problem for a strongly nonlinear second‐order elliptic equation in divergence form is approximated by primal hybrid finite element methods defined by Raviart and Thomas. Existence and uniqueness of the approximation are proved, and optimal order error estimates are established in various norms. © 1995 John Wiley&Sons, I

ISSN:0749-159X    

DOI:10.1002/num.1690110106

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractWe study the interpolation problem for solutions of the two‐dimensional Helmholtz equation, which are sampled along a line. The data are the function values and the normal derivatives at a discrete set of point sensors. Awave transformis used, analogous to the common Fourier transform. Theinversewave transform defines the Hilbert space for oscillatory Helmholtz solutions. We thereby introduce an interpolant that has some advantages over the usual sincxin the Whittaker–Shannon sampling in one dimension; in particular, coefficients of the two‐dimensional solution are invariant under translations and rotations of the sampling line. The analysis is relevant for the optical sampling problem by sensors on a screen. © 1995 John Wiley&Son

ISSN:0749-159X    

DOI:10.1002/num.1690110107

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractWe give an abstract stability result for finite element methods. It provides a general guideline for establishing the stability of finite element methods for a given norm once it is established with respect to another norm. The abstract result yields stability estimates of natural norms for finite element methods, which have recently been developed to stabilize effects like dominant convection, incompressibility constraints, or boundary conditions. These stability results simplify the error analysis of the discretizations and are helpful fin the convergence analysis of multigrid methods for the solution of the corresponding discrete problems. © 1995 John Wiley&Sons, Inc

ISSN:0749-159X    

DOI:10.1002/num.1690110108

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

摘要:

AbstractThis article is concerned with optimal control problems for the von Kármán equations with distributed controls. We first show that optimal solution exist. We then show that Lagrange multipliers may be used to enforce the consstraints and derive an optimality system from which optimal states and controls may be deduced. Finally, we define finite element approximations of solutions for the optimality system and derive error estimate for the approximations. © 1995 John Wiley&Sons, I

ISSN:0749-159X    

DOI:10.1002/num.1690110109

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY

ISSN:0749-159X    

DOI:10.1002/num.1690110102

出版商:John Wiley&Sons, Inc.    

年代:1995

数据来源: WILEY