bluuebunny/crossref_metadata_2025_split huggingface dataset:
A relaxation technique for the parabolized Navier–Stokes (PNS) equations
Authors: Kaul Upender K. 
Published: August 2005

AbstractA rapidly converging relaxation technique for the parabolized Navier–Stokes equation has been devised. The scheme is applicable in both supersonic and subsonic flows, but it is discussed here in the context of supersonic flows. The upstream propagating acoustic influence in the subsonic part of the flow is introduced semi‐implicitly through the streamwise momentum equation applied on the body, and through a forward‐differencing on the streamwise pressure gradient term in the interior. This procedure yields a new boundary condition on the energy in the total energy equation. The presser‐velocity system in the subsonic layer is coupled, but the positive time‐like marching characteristic of the governing equations is still maintained. The relaxation technique is demonstrated to work for a three‐dimensional flow over a cone‐flare in supersonic flight.
Curved beam element via penalty/mixed formulation for nonlinear in‐plane analysis
Authors: Akoussah Esenam , Beauliieu Denis , Dhatt Gouri 
Published: August 2005

AbstractThe problem of membrane locking for curved elements is discussed in detail. The penalty technique is used to develop a locking free curved beam element based on the Marguerre's relations. This formulation is then generalized to nonlinear analyses using updated Lagrangian description. Some examples are presented to assess the efficiency of the proposed model.
A strain softening element to model fibre pull‐out
Authors: Steven Grant P. 
Published: August 2005

AbstractIn order to model, with finite elements, the process of fracture in a fibre reinforced composite material a rod type element with strain softening in the form of a negative extensional stiffness is proposed. The acceptability, in a structural context, of such negative stiffness is examined and the performance of the element in modelling the fracture of fibre reinforced cement compact tension specimens is compared with experimental results.
Deforming finite elements for the numerical solution of the nonlinear inverse heat conduction problem
Authors: Mehta R. C. , Jayachandran T. 
Published: August 2005

AbstractA numerical solution of the nonlinear inverse heat conduction problem is obtained using an in‐line method in conjuction with the measured thermocouple temperature history. The deforming finite elements technique is used to treat initial time delay in temperature response due to thermocouple location. In the absence of elements deformation, the method reduces to the conventional Galerkin formulation. A three‐time level implicit scheme, which is unconditionally stable and convergent, is employed for the numerical solution. The temperature‐dependent thermophysical properties in the resulting matrices are evaluated at the intermediate level. The complication of solving a set of nonlinear algebraic equations at each step is avoided. Illustration of the technique is made on the one‐dimensional problem with a thermal radiation boundary condition. The results demonstrate that the method is remarkable in its stability to predict surface condition without debilitation.
A generalization of two‐dimensional theories of laminated composite plates
Authors: Reddy J. N. 
Published: August 2005

AbstractA general two‐dimensional shear deformation theory of laminated composite plates is presented. The theory account for a desired degree of approximation of the displacements through the laminate thickness. As special cases, the classical, first‐order (Reissner–Mindlin) and other shear deformation theories available in the literature can be deduced from the present theory.
Tau method approximate solution of highorder differential eigenvalue problems defined in the complex plane, with an application to orr‐sommerfeld stability equation
Authors: Liu K. M. , Ortiz E. L. 
Published: August 2005

AbstractRecent new formulations of the Tau method have made it possible to apply it to a variety of new problems. In this paper we consider the numerical estimation of complex eigenvalues of high‐order differential equations by using the Tau method. The example considered is Orr–Sommerfeld's stability equation, for which there is a considerable literature on high‐accuracy numerical estimations. Our numerical results compare favourably with the most accurate ones reported in the recent literature.
A sparse linear equations solver for 3D–regular domains
Authors: Lipitakis Elias A. , Evans David J. 
Published: August 2005

AbstractThe implementation of the Extended to Limit sparse LU factorization solution methods1 is given. Two FORTRAN subroutines for the approximate (or exact) factorization and the solution of resulting equations are supplied. The amount of fill‐in terms can be controlled by the user through parameters R1, R2, the limiting case being when the matrix is factorized exactly.
Further results on the accuracy of the SSpj algorithms
Authors: Wood W. L. 
Published: August 2005

AbstractIntuitively, it may that the single‐step algorithm SSpj, which depends on approximating the function in a time‐step by a polynomial of degree p, should give the same order error whether it is applied to a first‐or second‐order equation. This paper exaplains by direct analysis why the error in the function produced by SS22 is only 0(Δt) in general, whereas for SS21 it is 0(Δt2). This leads to the further result that for SSpj the function and all its derivatives up to and including the (p – 1)th are approximated with same order of accuracy. Numerical results are given for SS22 and SS32.
Comparison of 3‐D finite elements for fluid flow
Authors: Robichaud Michel P. , Tanguy Philippe A. 
Published: August 2005

AbstractSeveral new elements are compared to the standard trilinear velocity–constant pressure element (Q1 – P0) for the solution of the three‐dimensional Navier–Stokes equations by the finite element method. The test problem is the cubic wall‐driven cavity with solution sought at Reynolds numer of 400 and 3200. It is shown that the Q1 – P0 can be advantageously replaced by better elements and a choice among these elements is proposed.
Shallow shells under arbitrary loading: Analysis by the two‐surface truss model
Authors: Mbakogu F. C. , Pavlović M. N. 
Published: August 2005

AbstractThis paper is concerned with an extension of the two‐surface truss model—hitherto restricted to the analysis of shallow shells under normal loading—to the somewhat more general case of shallow shells under arbitrary loading. We begin with a brief review of the two‐surface truss model. Next, we show that our proposed extension is indeed quite straightforward once certain consequences of the two‐surface exposition of thinshell theory are fully appreciated. We then outline two alternative approaches to the incorporation of tangential surface into the truss model. Finally, we demonstrate the good working of the trussmodel scheme in the present context by means of a numerical example.
A simple error estimator in the finite element method
Authors: Rank E. , Zienkiewicz O. C. 
Published: August 2005

AbstractRecently, a new class of error indicators and estimators for the finite element methods has been introduced which is particularly easy to implement into existing finite element codes. This paper proves that the new indicators are equivalent to those analysed earlier by Babuska, thus showing that the rigorous mathematical results for the well‐known jump indicator apply also for the new ones.
Knowledge engineering enhancement of finite element analysis
Authors: Breitkopf Piotr , Kleiber Michal 
Published: August 2005

AbstractThis paper describes concepts behind the IQFEM which is an experimental knowledge based system for algorithm selection in nonlinear finite element analysis. Problems demanding human expertise in the FEM field are identified. The need to emulate this expertise by means of an appropriate expert system is emphasized. Knowledge base organization and symbolic inference principles, as employed in the system, are reviewed. The IQFEM has been developed in PASCAL using the 16‐bit personal computer. The paper describes the work in progress and no definite conclusions are stated.
Simulation of industrial cold forming processes
Authors: Hussin A. A. M. , Hartley P. , Sturgess C. E. N. , Rowe G. W. 
Published: August 2005

AbstractA microcomputer‐based system for the simulation of cold metalforming processes is described. The simulation uses a nonlinear elastic–plastic finite element method developed for use on a 16‐bit microcomputer. The suitability of such a system is demonstrated by reviewing its application to industrial forming processes such as heading and extrusion. The simulation system provides details of forming forces, metal flow, and stress and strain distributions which may be used as a guide to the structure and mechanical properties of the finished product.
Transport of solid materials within storage basins of river power plants: Software design and practical application
Authors: Heidinger R. , Baumhackl G. 
Published: August 2005

AbstractOver 60 per cent of the demand for electrical energy in Austria is covered by hydroelectric power plants. Problems arise within backwater areas of river power plants, causing storage loss by sedimentation of solid particles. Higher costs in construction, loss of energy and danger of inundation cause energy companies to simulate characteristics of this phenomenon numerically. The following considerations show that particular programming techniques enable the user to predict changes in river geometry within a short time and even create an individual set of sediment transport formulae within the software.
High order finite difference schemes to solve Poisson's equation in cylindrical symmetry
Authors: Mittal R. C. , Gahlaut Sanjeev 
Published: August 2005

AbstractIn the present work, finite difference schemes of second and fourth order are derived for the solution of Poisson's equation in cylindrical symmetry. The resulting system of linear equations is solved by a direct solver with the help of Hockney's method. The schemes are tested on two test problems whose exact solutions are known. The numerical results obtained by the finite difference schemes show that they produce accurate results.
A note on applications of adaptive finite elements to elastohydrodynamic lubrication problems
Authors: Wu S. R. , Oden J. T. 
Published: August 2005

AbstractAdaptive methods are applied to improve the finite element solutions for highly nonlinear elastohydrodynamic lubrication problem. A refinement scheme is developed which is based on the idea of equidistribution of local errors. Numerical experiments on the line contact problem show that the adaptive method is very effective in obtaining good approximations. Adaptive methods for point contact problems with light loads are also examined.
Geometric sensitivity analysis with isoparametric finite elements
Authors: Brockman R. A. 
Published: August 2005

AbstractThis paper presents the development of several analytical relationships for use in the gradient calculations common to sensitivity analysis and configuration optimization. The methods discussed are oriented toward two‐ and three‐dimensional continua modelled with isoparametric finite elements, and design parameters which control the geometric layout of the structure. The notable feature of these formulae is their simplicity, which leads to quick and systematic computational algorithms for most standard elements.
Optimum dynamic dampers for single‐degree‐of‐freedom systems
Authors: Ebrahimi Nader D. 
Published: August 2005

AbstractReducing the vibration amplitude of mechanical systems is an on‐going problem for engineers. This paper, which focuses on one aspect of the problem, discusses the design of optimum vibration absorbers for linear damped systems. After the optimum design problem is introduced, a numerical optimization strategy is implemented for the solution. The results are presented in the form of comprehensive design tables that can be readily used by designers since the parameters are given in terms of dimensionless variables. When the results of optimization are compared to the case of a system with no absorber, the comparison will show that the scheme presented in this paper significantly reduces the maximum vibration amplitude of the mechanical systems operating under the influence of harmonic excitation.
A note on invertible two‐dimensional quadratic finite element transformations
Authors: Baart M. L. , Mulder E. J. 
Published: August 2005

AbstractThis paper presents a simple algorithm for verifying the non‐singularity of parametric transformations with quadratic Jacobian determinants. The method is suitable for such transformations applied to all convex polygonal two‐dimensional master‐elements, but emphasis is placed on the triangle and the square. Geometric insight is used to curtail testing procedures where possible. The algorithm is compared for efficiency to a related procedure in which no use is made of the geometry of the implied curves. Results indicate that the geometric procedure, while slower in some cases owing to additional tests, is considerably more efficient for those cases where the geometry allows early termination of the algorithm.
A note on plasticity theory in matrix notation
Authors: Pedersen Pauli 
Published: August 2005

AbstractIn the matrix formulation of continuum mechanics, stress and strain tensors are contracted to vectors, and this lower order formulation has some advantages. However, due to an inconvenient contraction, the matrix formulation cannot be fully utilized in the theory of plasticity. The traditional contraction with engineering strains is rather artificial, and in the present note it is shown how the natural √2 contraction for both stresses and strains makes a very clean formulation possible. The importance of projection matrices is pointed out.
Modelling of thermal diffusion in three dimensions by the transmission line matrix method and the incorporation of nonlinear thermal properties
Authors: Pulko S. H. , Johns P. B. 
Published: August 2005

AbstractModelling of thermal diffusion in three dimensions by the TLM (transmission line matrix) method is described and the results compared with those obtained using finite element analysis. Two approaches to the incorporation of nonlinear properties in TLM routines are also described and compared.
A note on the optimum choice for penalty parameters
Authors: Nour‐Omid Bahram , Wriggers Peter 
Published: August 2005

AbstractThis paper looks at the numerical characteristics of penalty methods for evaluating the solution of symmetric systems of equations with imposed constraints. The sources of error resulting from this approach are identified and an estimate for the penalty parameter that minimizes this error is obtained. The results of the error analysis and the effect of penalty parameter on the accuracy and rates of convergence of the solution algorithm are demonstrated with the aid of some numerical examples.
Adaptive techniques in the finite element method
Authors: Zhu J. Z. , Zienkiewicz O. C. 
Published: August 2005

AbstractAn effective h‐version finite element adaptive strategy combined with mesh regeneration is presented. This is based on the error estimator developed in Reference 1. The rate of convergence of the adaptive procedure has been tested for some examples and very strong convergence observed. Unlike some existing h‐version adaptive procedures, a nearly optimal mesh of predicted accuracy can be obtained in one or two adaptive process steps.
Symbolic analysis of the reduced incompressible Navier‐Stokes equations
Authors: Fletcher C. A. J. , Armfield S. W. 
Published: August 2005

AbstractSymbolic analysis is described and used to show that the reduced Navier‐Stokes equations are parabolic due to the convection‐diffusion interaction, but are elliptic due to the interaction between the pressure field and the continuity equation. It is demonstrated that the introduction of a transverse pressure gradient term into the streamwise momentum equation will render the complete system non‐elliptic and amenable to solution via a single spatial march in the streamwise direction.
Integrals over boundaries at infinity for the boundary integral method may be ignored
Authors: Sofianos A. I. 
Published: August 2005

AbstractThe boundary integral equation method sometimes requires the integration of kernel functions times displacement or traction fields over boundaries at infinity. The value of these integrals in the case of two‐dimensional elasticity and the action of non‐self‐equilibrating force densities, which is especially relevant in geotechnical engineering, is not obvious. It has been proven that these integrals sum to zero.
From Kirchhoff to Mindlin plate elements
Authors: Aalto J. 
Published: August 2005

AbstractA procedure to generalize Kirchhoff thin plate finite elements so that they can be used for solving thick Mindlin plates is presented. Two typical discrete Kirchhoff elements, a triangular one and a quadrilateral one, are modified. Numerical results for a clamped circular plate show that the accuracy of the new Mindlin elements is the same as that of the original Kirchhoff elements and they can be used in the whole thickness range of Mindlin plate theory.
A simplified method for the dynamic analysis of shell structures
Authors: Gao Lin , Keming Sun , Menglin Lou 
Published: August 2005

AbstractAn efficient method suitable for the dynamic analysis of shell structures is introduced. The shell is partitioned into a series of strips, the vibration modes of which are taken as the basic vectors for co‐ordinate transformation. This approach highly reduces the degrees‐of‐freedom of the equation of motion and highly simplifies the computational effort, while good precision can still be ensured.
A finite element‐finite difference solution of three‐dimensional viscous‐inviscid interaction
Authors: Gülçat Ü. , Aslan A. R. 
Published: August 2005

AbstractBased on the concept of viscous‐inviscid interaction, a hybrid solution technique in studying external flow past three‐dimensional bodies is developed. The finite element method is employed to solve the inviscid part of the flow and the finite difference technique is utilized in solving the viscous part of the flow. This hybrid technique is applied to study the flow past a swept bump on a circular cylinder. The 8‐noded trilinear brick elements are used for the finite element formulation of the problem where the flow is considered potential. In the viscous part, however, three‐dimensional boundary‐layer equations simplified with small cross‐flow assumption and expressed in the surface co‐ordinates are solved utilizing the finite difference method. Numerical studies are made for both the laminar and the turbulent flow cases using the boundary‐layer edge velocity distribution obtained through inviscid solution. The results are compared with the available experimental data. The boundary‐layer edge velocity distribution is in good agreement with the experimental data; the prediction of the separation point for the laminar case is the same. For the turbulent flow case, the velocity profiles in the flow direction when compared to the measurements are overall in reasonably good agreement, and the discrepancies are due to small cross‐flow assumption. However, the agreement concerning the wall shear stress component in the flow direction is more satisfactory.
Solution of full and deficient rank linear equations
Authors: Tewarson R. P. , Jen J. F. 
Published: August 2005

AbstractAn algorithm for computing the solution of a linear system of algebraic equations is described. If the system is rank deficient, then the minimum norm least‐squares solution is obtained. The method utilizes Gaussian elimination with scaled partial pivoting and (in rank deficient case) orthogonal triangularizations on the remaining coefficient matrix.
Element‐by‐element vector and parallel computations
Authors: Carey G. F. , Barragy E. , McLay R. , Sharma M. 
Published: August 2005

AbstractVector and parallel algorithms for finite‐element analysis using the element‐by‐element (EBE) data structure are developed. The algorithms are based on the EBE approach in conjunction with gradient‐type iterative solution. The essential idea is to exploit the independent dense local‐element matrix‐vector calculations and reconfigure them to take advantage of vector or parallel processing capabilities. The ideas also are well suited to finite‐element adaptive refinement computations. Specific algorithmic details related to the implementations are given, together with results of speed‐up performance studies conducted on the vector and parallel architectures. The basic vector and parallel versions of the matrix‐vector product for the EBE scheme are very straightforward modifications of the EBE algorithm, requiring little coding change.
On a modified streamline curvature method for the Euler equations
Authors: Cordova Jeffrey Q. , Pearson Carl E. 
Published: August 2005

AbstractA modification of the streamline curvature method leads to a quasilinear second‐order partial differential equation for the streamline coordinate function. The existence of a stream function is not required. The method is applied to subsonic and supersonic nozzle flow, and to axially symmetric flow with swirl. For many situation, the associated numerical method is both fast and accurate.
Simulation techniques for multiphase and multicomponent flows
Authors: Ewing Richard E. , Espedal Magne S. , Puckett Jay A. , Schmidt Richard J. 
Published: August 2005

AbstractThe simulation of multiphase and multicomponent fluid flows often requires large coupled systems of nonlinear partial differential equations. These equations are convection‐dominated, with important local diffusive effects. An operator splitting technique is used to address these different phenomena. Adaptive local grid refinement methods are then presented to resolve the moving internal boundary layers which arise and often govern the mass transfer between the phases. Owing to the large size of many application, efficiency in computation is critical. Concepts of domain decomposition for dynamic adaptive grid refinement are presented. Techniques for dividing the problems into pieces for parallel computation on separate processors are also discussed.
Effects of geometric nonlinearities on explicit time integrators
Authors: Neal Mark O. , Belytschko Ted 
Published: August 2005

AbstractThe effect of follower forces and initial stresses on the stability of the central difference method is studied. As a model, bar and beam elements are considered by means of the element eigenvalue inequality. It is shown that both follower‐force pressure loads and tensile initial stresses decrease the stable timestep but the decrease becomes significant only when the pressure or stress is greater than about a tenth of the tangent modulus.
On some recent evolutions in personal supercomputing and workstation graphics
Authors: Hajjar J. F. , Martha L. F. , O'Connor T. F. , Abel J. F. 
Published: August 2005

AbstractRecent hardware advances for both enhanced computing and interactive graphics are used to improve the effectiveness of three‐dimensional engineering simulations. The two examples presented, drawn from structural engineering, deal with the fully nonlinear transient dynamic analysis of frames and boundary element stress analysis.
The versatility of automatic mesh generators based on tree structures and advanced geometric constructs
Authors: Shephard Mark S. , Baehmann Peggy L. , Grice Kurt R. 
Published: August 2005

AbstractThe ability of the finite octree and finite quadtree automatic mesh generators to satisfy effectively a wide variety of meshing capabilities is demonstrated. Areas considered include the ability to integrate easily with geometric modelling systems, versatile interactive mesh control functions, the ability to reorder unknowns directly from the finite element data structure and the ability to support automated finite element modelling.