bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability of parallel flows by the finite element method
Authors: Saraph V. R. , Rao B. Vasudeva , Panikar J. T. 
Published: August 2005

AbstractThis paper presents and results obtained from the stabilitystudies of plane Poiseuille flow and magnetohydrodynamic flow by the finite element method. Applying Galerkin's weighted residual method and introducing the interpolation function in the exponetial form with respect to time, the governing flow equations are reduced to an eigenvalue problem. This formulation is much simpler than that of the asymptotic expansion method. Solutions are obtained directly in terms of velocity and pressure. Results of the critical Reynolds number obtained by this method compare well with those of other methods for plane Poiseuille flow and magnetohydrodynamic flow.
Finite dynamic element formulation for a plane triangular element
Authors: Gupta K. K. 
Published: August 2005

AbstractThe higher order dynamic correction terms for the stiffness and inertia matrices associated with a triangular plane stress‐strain finite dynamic element are developed in detail. Numerical results presented indicate that the adoption of these matrices along with a suitable quadratic matrix eigenproblem solver effects a significant economy in the free vibration solution of structures when compared with the analysis based on the usual finite element procedure.A FORTRAN IV computer program listing of the various relevant element matrices is also presented in the Appendix.
On the implementation of an application oriented software system
Authors: Peters F. J. 
Published: August 2005

AbstractSome tools are presented that may be used when implementing an application oriented software system. FEMSYS, a system for calculations based on the finite element method, will serve as example. Features of a simple problem oriented language and its parsing are treated and also a generally applicable data structure for both internal and external data storage. It is indicated how a system can be implemented which is suited to the solution of both standard and non‐standard problems.
Finite element solutions of convective diffusion problems
Authors: Barrett K. E. , Demunshi G. 
Published: August 2005

AbstractThree weighted residual methods are used to analyse several linear and nonlinear model problems related to the stream function–vorticity formulation of the Navier–Stokes equations. These methods are then used to solve the driven cavity problem. The results obtained at Reynolds numbers of 100 and 400 compare very favourably with those obtained by finite difference and spline methods on meshes using at least four times as many mesh points.
On inversion of complex matrices
Authors: Zielinski Adam 
Published: August 2005

AbstractA method is presented for inverting an n × n complex matrix M = A + jB by using a real matrix inversion. The approach avoids the requirements of inverting a 2n × 2n real matrix as well as non‐singularity assumptions placed on A or B, or A + B, or A − B, as required by earlier methods.
Dynamic response of strip footings on elastic halfspace
Authors: Dasgupta S. P. , Rao N. S. V. Kameswara 
Published: August 2005

AbstractDynamic response of strip footings resting on a soil medium, idealized as an elastic halfspace, is obtained using the finite element discretization technique with constant strain rectangular elements consisting of 4CST elements. Boundary stresses have been computed using a combination of Rayleigh wave absorbing boundaries (RAB) and standard vicous boundaries (SVB). The influences of contact pressure distributions at the footing—soil interface, mass and frequency ratios on the dynamic response of a strip footing are studied. Effects of embedment, static surcharge, nonhomogeneity and nonlinear constitutive relations are shown. Results are compared with the existing solution and are presented graphically.
Some properties of a hybrid element method for water waves
Authors: Aranha J. A. , Mei C. C. , Yue D. K. P. 
Published: August 2005

AbstractTwo properties of hybrid element method for diffraction and radiation of water waves are examined. For long waves in shallow water the method is shown to give a unique solution for all frequencies. Thus, unlike several other known methods, there are no irregular frequencies for which the approximating matrix equation is singluar. For a sea of arbitrary depth, it is shown that all known global identities such as reciprocity and energy theorems are preserved by the discrete solution. Thus, satisfaction of these identities by the numerical solution is only a necessary but by no means sufficient condition for accuracy.
Difference schemes or element schemes?
Authors: Cushman John H. 
Published: August 2005

AbstractSeveral examples are presented to illustrate how standard finite differnce schemes for the wave eqation (e.g. Lax–Wendroff, Leafrog, etc.) can be developed from finite element analysis. The development of the diffrence schemes from the element schemes is made possible by using Galerkin's method on both the spacial and temporal dimensions.
An alternative interpretation of superconvergence
Authors: Marshall Robert S. 
Published: August 2005

AbstractThe superconvergent property of the discrete solution to certain one‐dimensional problems is examined in the context of the weighted residual difference equations and their conservation properties. The difference equations are shown to satisfy the differential equation exactly at nodes and reproduce the derivatives at boundary nodes. The exact values for the first derivative at interior nodes follow from the conservation property when applied locally.
New developments in the inelastic analysis of quasistatic and dynamic problems
Authors: Argyris J. H. , St. Doltsinis J. , Willam K. J. 
Published: August 2005

AbstractThe computational aspects are examined for the numerical analysis of inelastic structures and continua. In this context, the tracing of quasistatic and dynamic motions is considered with particular emphasis on the interaction of nonlinear and transient problems.In the first part, explicit and implicit solution schemes are developed for the numerical integration of inelastic first‐order rte processes governing creep, viscoelasticity and viscoplasticity. In the second part, the exposition is extended to second‐order inertial problems and in particular to the field of dynamic plasticity, devoting special attention to the kinematics of finite deformation problems.
Derivation of first‐passage time distribution of a single lift for arbitrary traffic
Authors: Levy D. , Alexandrovitz A. 
Published: August 2005

AbstractThe distribution of the first‐passage time is of decisive importance in lift (elevator) design. It yields the easure of performance of the system, the expected number of stops, the interval (i. e. time elapsed between two successive departures from a given floor) and many other parameters and factors determining the required number of lifts in a building. The derivation is based on the transition probability matrix of the operation policy, and consists in solving a system of linear equations.
Buckling of skew plate structures using B‐spline functions
Authors: Mizusawa T. , Kajita T. , Naruoka M. 
Published: August 2005

AbstractThis paper presents a general procedure for calculating the buckling of stiffened skew plates by the Rayleigh‐Ritz method with B‐spline functions as co‐ordinate functions.Convergence of the solutions is investigated in a few typical cases and is found satisfactory. The results are compared with existing values based on other numerical methods and found to be in good agreement. Buckling characteristics of stiffened skew plates are also studies with varying stiffness parameters of stiffeners, skew angles and aspect ratios.
Numerical prediction of separated flows
Authors: Atkins D. J. , Maskell S. J. , Patrick M. A. 
Published: August 2005

AbstractUpwind and central difference schemes for laminar and turbulent flows over a step in a two‐dimensional channel are compared with each other and with experiment. Vorticity ω and stream function ψ are used as dependent variables and it is shown that an upwind difference method can give predictions which agree with experiment for high Reynolds number flows. The numerical implementation of the boundary conditions is found critically to determine the solutions obtained. Explicit prescription of ψ and ω at the inlet leads to incorrect values of the inlet velocity component perpendicular to the flow and a solution that does not agree with experiment. Experimental evidence is not available at low Reynolds numbers, but it is found that upwind differences give recirculation zones 8 per cent shorter and 8 per cent less intense than the more conventional conditionally stable central difference method.The distribution of the false diffusion effect in the upwind scheme is considered, and it is shown by use of a simple example that previous statements as to possible minimization of this effect are not generally true.The difficulty of determining the pressure distribution from the vorticity and stream function model is analysed and illustrated.Further, turbulent separated flows are seen to contain regions where two‐dimensional time‐dependent flow does not exist, and conventional theories do not give good results.
The global element method for stationary advective problems
Authors: Haj A. , Phillips C. , Delves L. M. 
Published: August 2005

AbstractWe extend the variation principle used in the global element method for self‐adjoint elliptic problems1, to problems containing advective terms. Used with the global element formalism, the extended principle yields a uniform framework for treating advective or boundary layer problems, with the attractive feature that the implicit treatment of interface conditions between elements yields an effective decoupling between ‘boundary layer’ and ‘interior’ parts of the solution. As a numerical example, we solve the one‐dimensional model problem of Christie and Mitchell3, obtaining high accuracy for Peclet numbers up to 106 with no sign of instability. These results suggest that, given a suitable choice of global elements, the decoupling is very effective in damping the oscillations found in standard finite difference or finite element treatment.
Primitive variable finite element formulations for steady viscous flows
Authors: Hutton S. G. , Exeter M. K. , Fussey D. E. , Webster J. J. , Rigon C. 
Published: August 2005

AbstractThe solution of incompressible, viscous flow problems using the primitive variable finite element approach is formulated in a coherent and physically reasoned exposition. In particular, it is shown that terms associated with changes in momentum caused by lack of mass conservation should logically be included in the governing equations. Previous formulations have not considered this possibility. Numerical results are presented to show the effect of inclusion of these extra terms; however, it is concluded from the numerical results for the specific case which was tested that there is no obvious benefit obtained by including these terms.
Response of Coastal harbours
Authors: Mattioli Franco , Tinti Stefano 
Published: August 2005

AbstractA numerical method able to evaluate the response of harbours of constant depth to periodic plane waves in the presence headlands of breakwaters near the harbour mouth is described and tested on a particular case.The method, based on Green's function theory, is rather general, and can also treat the response of an off‐shore harbour, as well as the diffraction field due to only breakwaters or headlands, when the interaction with the coastline must be taken into account.
The w‐plane finite element method for the solution of scalar field problems in two dimensions
Authors: Nath B. , Jamshidi J. 
Published: August 2005

AbstractA simple, efficient finite element method has been presented for the solution of a variety of scalar field problems in two dimensions. It is based on the mapping of the physical problem domain into an ‘image’ domain in the w‐plane. The governing equation(s) and the boundary conditions in the physical plane are also appropriately transformed into the w‐plane. The processes of standard finite element analysis are then implemented to obtain a solution in the w‐plane.The method has been explained in detail, with illustrative examples where appropriate; it has several important advantages over the standard finite element method, particularly for the solution of infinite or semi‐infinite domain problems. The method has been demonstrated to be simple, efficient, economical and potentially capable of dealing with a large repartoire of two‐dimensional problems, including non‐homogeneity, nonlinearity, etc.
A numerical method for solving two‐point boundary value problems for nonlinear ordinary differential equations
Authors: Tewarson R. P. 
Published: August 2005

AbstractA numerical method for solving two‐point boundary value problems associated with systems of first‐order nonlinear ordinary differential equations is described. It needs four function evaluations at each point and is of order h6, where h is the space chop. Results of computational experiments, which include perturbation of the initial conditions, comparing this method with other known methods are given.
On the use of central difference scheme for Navier–Strokes equations
Authors: Gupta Murli M. , Manohar Ram P. 
Published: August 2005

AbstractBoth the central and upwind difference schemes are commonaly employed to solve the Navier‐Stokes equations governing the two‐dimensional laminar flow of an incompressible laminar flow of an incompressible viscous fluid. By a judicious choice of a damping parameter and using direct methods for solving the systems of linear equations appearing in an iterative procedure, the central difference scheme could be made to give convergent results even for large Reynolds numbers. Using a model problem of flow through a driven square cavity it is shown that the converged results so obtained become progressively oscillatory and inaccurate as the Reynolds number increases. It is known that the central difference scheme gives more accurate results than the upwind difference scheme, at least for small values of Reynolds number. However, for a reasonably small mesh size the numerical solutions obtained by using either the central or the upwind difference scheme do not differ appreciably at low Reynolds numbers. There is a small range of Reynolds numbers for which the central difference scheme may yield more accurate results than the upwind difference scheme; however, this range is not known a priori.
A method for incorporating free boundaries with surface tension in finite element fluid‐flow simulators
Authors: Ruschak Kenneth J. 
Published: August 2005

AbstractA boundary‐location method is developed for finite element simulation of steady, two‐dimensional flows of Newtonian liquid with free boundaries. In the method, boundary shape and position and the velocity and pressure fields are determined simultaneously. Inertial, viscous, gravitational, and surface tension effects are included in the development. The complete set of nonlinear finite element equations is solved by a modified frontal method combined with Newton‐Raphson iteration to speed convergence. The finite element used to illustrate the method approximates the pressure as a piecewise constant function and the velocity and free boundaries as piecewise linear functions. Example calculations for flow from a slit show that the method can be effective.
A modified plasticity theory for porous metals
Authors: Gadala M. S. , Mullins M. L. , Dokainish M. A. 
Published: August 2005

AbstractA plasticity theory for porous metals is proposed. A simple model of a porous materials is analysed by the finite element method. Small strain elastic–plastic analysis provides stress–strain curves, yield stressed and incremental plastic strain vectors for different void ratios. An assessment is made of an existing yield criterion for porous metals. A modified yield criterion and plastic potential function and, consequently, different plasticity equations are given. Reasonable agreement is obtained between the present numerical results and previous results in the literature.
An economical storage organization for large and small finite element systems with reference to the application of iterative approximation methods to nonlinear material behaviour
Authors: Fengels W. , Troost A. 
Published: August 2005

AbstractThe method of data transfer from the peripheral storage unit to the central processor unit, when dealing with large solution systems, is of greater importance, as each access of peripheral stored data interrupts the active flow of arithmetic operation in the central processor core. When solving a large number of symmetrical positive‐definite equations this generally leads to difficulties in channel interaction and priority, possibly even to the breakdown of the computer system or to uneconomical computing times. The problem increases when considering the iterative approximation of nonlinear problems; further still, when using the frontal solution method. It will be shown that this difficulty can be avoided by inserting two different types of buffers—a micro‐buffer and a macro‐buffer—into the data transfer between the central memory and an arbitrary peripheral storage unit. This method should primarily be used in those finite element (FE) programs which are based on the ‘slow’ BACKSPACE‐READ‐BACKSPACE commands, but even in the case of peripheral storage units such as magnetic discs (random access) or magnetic tape machines (working in one or two directions) the computing time and channel control can successfully be improved. A second achievement of this procedure is the possibility of applying a FE program economically, not only to large element systems and elements of a ‘higher order’ but also with good results for small element systems, e.g. when investigating nonlinear material behaviour with simple element types and geometrical structure. Another purpose of this text is to recommend the FORTRAN subroutine in the Appendix, whose novel features make it a useful supplement to ‘nonlinear’ FE programs.
Techniques for developing ‘special’ finite element shape functions with particular reference to singularities
Authors: Hughes Thomas J. R. , Akin J. E. 
Published: August 2005

AbstractA concise and efficient algorithm is presented for deriving finite element shape functions from an arbitrary set of independent functions. Based on special one‐dimensional interpolatory schemes derived via the algorithm, a variety of two‐ and three‐dimensional interpolatory schemes are developed which are useful for modelling singular behaviour. The methodology presented is general and may be fruitfully applied to the development of ‘special’ finite element shape functions for a variety of other situations.
Transition finite elements for three‐dimensional stress analysis
Authors: Surana Karan S. 
Published: August 2005

AbstractThis paper presents isoparametric formulation for the three‐dimensional transition finite elements. The transition finite elements are necessary for applications requiring the use of three‐dimensional isoparametric solid elements and the curved shell elements. These elements provide proper connections between the two portions of the structure modelled with three‐dimensional solids and the curved shell elements. The element properties are derived and presented in detail. Numerical examples are also presented to demonstrate the accuracy and the applications of such elements in three‐dimensional stress analysis.
The synthesis of near‐optimum finite element meshes with interactive computer graphics
Authors: Shephard Mark S. , Gallagher Richard H. , Abel John F. 
Published: August 2005

AbstractA new approach to the generation of near‐optimum finite element meshes is presented. Like other current methods, the procedure presented uses the results of a previous analysis to improve the idealization, but unlike other procedures a new element mesh is generated in each cycle with the aid of interactive computer graphics. The procedure generates near‐optimum two‐dimensional meshes on one cycle employing a grid optimization criterion based on variations in the strain energy density and using a software system which operates like an interactive finite element preprocessor. The example problems presented demonstrate the efficiency and flexibility of the approach.
Modification of iterative processes for improved convergence characteristics
Authors: Lawther R. 
Published: August 2005

AbstractA method for improving the convergence rate of iterative processes is presented. This method monitors the sequence of approximations produced by an iterative process, and generates a new iterative process, or sequence of processes, each with more rapid convergence characteristics than the previous one. This method of process modification can be applied to many iterative techniques currently in use. Examples of application of the method are given, using both nonlinear and linear systems. In one of these examples it is shown that the method can be applied to a divergent iterative process, producing a convergent one. It is also shown how the technique can be applied to equations of one variable, yielding a method with convergence characteristics similar to those of Newton's method, but without the explicit calculation of derivatives.
An application of Keller's method to the solution of an eighth‐order nonlinear boundary value problem
Authors: Balu R. 
Published: August 2005

AbstractAn efficient implicit finite difference method, called the Keller's box scheme, is applied to solve an eighth‐order nonlinear two‐point boundary value problem. The example considered here is the compressible boundary layer equations at a general three‐dimensional stagnation point. The solutions obtained are compared with results from other methods and the potential advantages of the method are demonstrated.
Nonlinear analysis of liquid motion in a container subjected to forced pitching oscillation
Authors: Nakayama Tsukasa , Washizu Kyuichiro 
Published: August 2005

AbstractA nonlinear analysis is carried out for the motion of the inviscid, incompressible fluid in a two‐dimensional, rigid, open container which is subjected to forced sinusoidal pitching oscillation. Firstly, the problem is defined as a nonlinear initial‐boundary value problem by the use of a governing differential equation and boundary conditions. Next, the problem is formulated in the form of a pseudo‐variational principle, which provides a basis for our discretization. The finite element method and finite difference method are used spacewise and timewise, respectively. Due to the strong nonlinearity of the problem, an incremental method is used for the numerical analysis. Numerical results obtained by the present method are compared with solutions of the linear theory and experimental data. The difference between linear and nonlinear analysis has been clearly indicated.
Numerical analysis of the steady‐state behaviour of a MOS field effect transistor
Authors: Akers Lex A. , Portnoy William M. 
Published: August 2005

AbstractA numerical scheme is developed to simulate the non‐isothermal steady‐state behaviour of a MOS field effect transistor. In a desire to develop a fast, stable numerical scheme, physical instabilities were eliminated by using a simplified device model. The numerical technique developed permits a computer solution of the majority carrier transport equation, the nonlinear heat conduction equation, in which the heat generation term is obtained from the solution of the transport equation, and a number of auxiliary differential equations.The simplified model of the MOS transistor adopted will not, of course, produce any information on the actual operation of the short channel MOS transistor of practical interest today, but the numerical scheme can be extended to simulate short channel models that are of great practical interest.