bluuebunny/crossref_metadata_2025_split huggingface dataset:
Natural convection in an enclosure with a vertical baffle
Authors: Zimmerman E. , Acharya S. 
Published: August 2005

AbstractA numerical study is made of natural convection in an enclosure with a vertical, finitely conducting baffle. The end‐wall is assumed to be either perfectly conducting or adiabatic. Predicted flow and isotherm patterns indicate the existence of strong thermal stratification in the baffle/cold wall region and are in qualitative agreement with reported experimental results. The baffle strongly influences the hot‐wall Nusselt number distribution, but has a weaker effect on the cold‐wall Nusselt number distribution. The predicted Nusselt numbers show satisfactory agreement with the high Rayleigh number based experimental correlation of Lin and Bejan in a partially divided enclosure of aspect ratio 0.3.
Predictions of the combustor coannular swirling flowfield using a modified turbulent kinetic energy equation
Authors: Chao Y. C. , Ho W. C. , Liu S. S. 
Published: August 2005

AbstractA modified model based on the turbulent kinetic energy equation is used to predict the recirculating swirling flowfield. The model properly includes the wave and oscillation nature of the swirling flow and redefines the energy budget in the turbulent kinetic energy equation. This brings about significant improvements in the recirculation zone as well as the recovery region, as compared with the results from models used by Rodi and Launder et al. of the Richardson number type corrections in the dissipation equation.
A pressure cycle control algorithm for superplastic forming
Authors: Bonet J. , Wargadipura A. H. S. , Wood R. D. 
Published: August 2005

AbstractThe calculation of the pressure cycle is of crucial importance for the successful development of a thin sheet superplastic forming process. The pressure cycle must be such that the forming time is minimized while maintaining a strain rate that maximizes the strain‐rate sensitivity parameter, in order to reduce the propensity of the material to undergo localized necking. One way of dealing with this problem is to control the pressure by constraining the maximum equivalent strain rate. This paper presents a general numerical algorithm for achieving such control, in conjunction with a finite element analysis of the forming process. Three examples are given of strain‐rate controlled pressure cycles for the forming of a plane‐strain strip.
Lifting aerofoil calculations using von Mises variables
Authors: Naeem R. K. , Barron Ronald M. 
Published: August 2005

AbstractA natural streamline coordinate system approach has been developed for steady two‐dimensional incompressible lifting flow problems. Flow equations with appropriate boundary conditions are presented in terms of von Mises coordinates (x, ψ), where ψ is the streamfunction for the flow. The finite difference method is used to discretize the non‐linear elliptic equation describing the flow. Favourable agreement with available results is obtained.
Optimal structural remodelling — simulation by virtual distortions
Authors: Holnicki‐Szulc Jan 
Published: August 2005

AbstractA numerical method for simulation of optimal structural redesign by virtual distortions is presented. First, the idea of the simulation technique is discussed in the case of truss structures and then the application to the case of in‐plane loaded plates is made. The optimal results for the class of continuous solutions as well as for Michell's pseudocontinuums are reached.
Iterative improvement of eigensolutions from reduced matrices
Authors: Sauer G. 
Published: August 2005

AbstractThe Guyan method to reduce stiffness and mass matrices of linear structures is widely used in engineering practice. However, it introduces errors in the reduced mass matrix, and the eigensolutions based on this matrix are reliable only for the lowest modes. Additionally a certain skill is required to select appropriate analysis co‐ordinates. But the eigensolutions from the reduced matrices can easily be improved by a straightforward iteration procedure. This procedure is presented. The achievable improvements in accuracy are demonstrated by an example.
Five‐point FTCS finite‐difference methods for heat conduction
Authors: Noye B. J. 
Published: August 2005

AbstractA family of five‐point second‐order forward‐time centrred‐space (FTCS) explicit finite‐difference equations for solving the one‐dimensional heat conduction (diffusion) equation with constant coefficients and Dirichlet boundary conditions is described. Some members have stability ranges larger than that of the standard three‐point FTCS equation, others are more accurate, and some are both more accurate and more stable. Values at grid points adjacent to boundaries are computed by means of an explicit procedure with stability and accuracy matching that of the equation used at interior grid points.
A model of one‐dimensional primary and secondary consolidation, based on flow channel considerations
Authors: Thomas H. R. 
Published: August 2005

AbstractThe possible influence of one aspect of flow channel characteristics on consolidation behaviour is addressed. In particular, the effect of potential distributions between particles forms the basis for the work. An attempt is made to represent this microscopic phenomenon, at the macroscopic level, by the mechanistic approach that the coefficient of permeability varies as a function of the remaining excess pore water pressure. It is shown that the approach proposed is capable of reproducing the classical experimentally observed one‐dimensional consolidation settlement curves of viscous clay. Primary and secondary compression behaviour is modelled.
Procedures for residual equilibration and local error estimation in the finite element method
Authors: Kelly D. W. , Isles J. D. 
Published: August 2005

AbstractProcedures to enforce equilibration of residuals and determine complementary a posteriori error estimates for linear elasticity have been published elsewhere.1−4 Methods for determining the error in stress and displacement have also been proposed.3 Here we discuss an extension to the procedure for equilibrating the residuals and apply it to a simple example. Results for the error in stress and displacement are presented.
On the front‐tracking scheme for phase‐change problems
Authors: Askar Hasan G. , Abdul‐Latif Wisal 
Published: August 2005

AbstractPhase‐change problems can be solved numerically for the temperature distribution when accompanied by explicit reference to the position of the front at each time interval. An improved front‐tracking scheme provides accurate determination of the phase front in the different stages of analysis. The front is made to coincide with a created grid node throughout the numerical analysis. The scheme utilizes a combination of the finite‐difference and finite‐element methods for obtaining the solution of the phase‐change problem.
A new boundary integral equation‐finite‐element method for clamped orthotropic plate bending problems
Authors: Shi G. , Bezine G. 
Published: August 2005

AbstractIn this paper, a simplified boundary integral equation‐‐finite‐element method is proposed for the bending analysis of thin clamped orthotropic plates according to Kirchhoff's theory. The solution procedure is based on the direct boundary element method earlier developed for isotropic plate bending problems. The integral equations necessary for solving the orthotropic plate bending problem are derived after transformation of such a problem into an equivalent isotropic plate bending problem by introducing an unknown transverse loading distributed in the interior domain of the plate. A simple discretization scheme is described in this paper for the plate boundary and its interior domain. Some computational examples are presented in this paper, and the numerical results illustrate a satisfactory accuracy of the method.
Spatially regularized solution of inverse elasticity problems using the BEM
Authors: Zabaras N. , Morellas V. , Schnur D. 
Published: August 2005

AbstractThis paper is concerned with solution by the boundary element method (BEM) of a certain class of inverse linear elastic problems using the spatial regularization method. More specifically, the problem of calculating the boundary and internal conditions on a deformed specimen given approximate information on the displacements at discrete ‘sensor locations’ in the specimen is discussed. The solution algorithm employs a sensitivity analysis and a least‐squares minimization of the difference between the calculated and measured displacements at each sensor location. The ideas presented here can be applied to contact problems where measurements of the deformation at the contact area are difficult.
Elastic‐plastic hybrid/mixed finite‐element method and its application to the non‐uniform tension of square sheet metal
Authors: Hu Ping , Zhou Dajun 
Published: August 2005

AbstractA new elastic‐plastic hybrid/mixed finite‐element method, presented in this paper, is used for the numerical analysis of non‐uniform tension and buckling behaviour of square sheet metal under the diagonal tensile condition. The total displacement, stress and strain fields as well as their evolution up to a critical buckling condition are obtained for comparison with the experimental results by using the Moire method. It is found that the FEM can be a useful tool for studying the complex elastic‐plastic deformation problem in sheet‐metal forming processes.
On the construction of physical systems from spectral data
Authors: Zimoch R. Z. 
Published: August 2005

AbstractThis paper presents an algorithm for the solution of the inverse problem for a matrix differential equation of the form Aẍ + Bẋ + Cx = 0. In the method use is made of the Taylor formula for a matrix function of many variables. It is shown that the algorithm is always convergent. The paper includes a description of the appropriate algorithms and numerical examples.
On higher‐order asymptotic factorization of non‐linear operators
Authors: McMorran Andrew G. , Cooke Charlie H. 
Published: August 2005

AbstractOperator splitting for evolution equations which involve non‐linear differential operators is investigated. The occurrence of third‐orderaccurate multifactor splittings which are characterized by all‐positive fractional steps and which involve at most four factors is discovered. This result is surprising, as a recent investigation by Sheng (1989), of evolution equations involving general linear operators, establishes that no third‐orderaccurate factional‐step splitting having all‐positive fractional steps exists, regardless of the number of factors attempted. However, the present investigation indicates it is unlikely that Sheng's result has much bearing on the existence of positive‐step splittings for non‐linear equations. In addition to the result mentioned above, with n = 3, 4, 5, another case is exhibited of a non‐linear equation which permits all‐positive step, n‐thorder splittings requiring only n + 1 factors. Indeed, a pathological case is examined of a partial differential equation with an annihilating operator which permits k‐factor, nth‐order splittings, for k > 1 and n > 1. Thus, for the non‐linear case, one should expect only the unexpected. Finally, the idea of equivalent splittings for linear aganist non‐linear equations is considered. For a particular equation, all splittings having five factors or less, which are obtained by considering a linearization are shown applicable also to the non‐linear case. However, there exists a four‐factor all‐positive step splitting of the non‐linear equation which is not discovered by the linearized approach.
Bifurcations of an oscillator to two‐harmonic excitation
Authors: Leung A. Y. T. , Fung T. C. 
Published: August 2005

AbstractThe incremental harmonic balance method has been successful for harmonic excitation. It is extended to determine the steady‐state solutions of a non‐linear oscillator subject to periodic (two‐harmonic) excitation. Higher‐order subharmonic solutions result from bifurcations. As the bifurcation process continues in an accelerated rate, chaotic solutions are obtained when no simple subharmonic solution coexists. When periodic solutions do coexist, the final steady‐state solution depends on the initial conditions. The evolution of the amplitude against the system parameters can be recorded on a bifurcation graph. An initial bifurcation graph is constructed when one of the system parameters varies. Neighbouring bifurcation graphs when other system parameters are changing are obtained in an incremental manner. If only the boundaries dividing the qualitatively different solutions are constructed, a parametric diagram is obtained. The characteristic of the solutions can be read directly from the diagram. For an oscillator subject to two‐harmonic excitation, the parametric diagram is found to be qualitatively different from those with one‐harmonic excitation. The parametric diagram is highly foliated when many stable and unstable higher‐order subharmonic solutions coexist at the same time under some combination of conditions. It is possible that the periodic solutions disappear suddenly and give way to chaotic solutions due to a small change in the system parameters without undergoing period doubling.
Non‐associative Drucker‐Prager plasticity at finite strains
Authors: Hofstetter G. , Taylor R. L. 
Published: August 2005

AbstractA straightforward extension of the return mapping algorithm for J2‐plasticity at finite strains to a non‐associative Drucker‐Prager yield criterion, assuming elastic volumetric response, is presented. It is shown that the concept of plastic incompressibility, assumed at the outset, does not hold for a certain range of stresses.
Modelling of turbulent transonic flow around aerofoils and wings
Authors: Müller Bernhard , Rizzi Arthur 
Published: August 2005

AbstractTurbulent flows around aerofoils and wings are simulated by solving the two‐and three‐dimensional Navier‐Stokes equations in quadrilaterals and hexahedrons, respectively. Turbulent flow is described by an algebraic eddy viscosity model. Boundary‐conforming O‐and O‐Otype meshes are generated by the transfinite interpolation method. The finite‐volume technique is employed for spatial discretization using two cells in each computational co‐ordinate direction more than the conventional approach to evaluate the viscous fluxes. An explicit three‐stage Runge–Kutta scheme is used for time integration. The method is applied to compute turbulent transonic flow over the NACA 0012 aerofoil and the ONERA M6 wing. The results are compared with experimental and computational data.
A simplified approach to calculate the damping ratio matrix for multiple degree of freedom vibration systems
Authors: Wilson J. M. , Man Liu 
Published: August 2005

AbstractIn modal analysis of damping systems, the criteria matrix of damping ratios is of importance for both experiments in identification of structure parameters and theoretical analysis of assessing dynamical response. In a single degree of freedom system, the damping ratio can be defined easily and obtained by some simple calculations. So the vibration response envelope can be predicted, which is important for passive isolation and active control of vibration in dynamical design. Likewise, in a multiple degree of freedom system, the concept can be defined similarly to the single degree of freedom,1 while it involves complicated manipulations and calculations to obtain the damping ratio matrix in terms of mass, damping and stiffness matrices. Some available stimulating references have discussed the damping ratio matrix and presented some alternative criteria matrices.1–4However, the final formula to evaluate the damping ratios is quite complex and it needs several eigensolutions. If the mass matrix is formed by uniform interpolation to the stiffness, the calculations are even greater than that in the state space calculating eigensolutions directly. Regarding these, a new approach is presented in this paper in terms of modal parameters to calculate the damping ratio matrix. Therefore, the damping ratio matrix takes the parallel form to the single degree of freedom system, and the calculations are greatly reduced. Further, the paper also discusses the case of incomplete sets of eigenpairs, which is of practical importance since for most large structures the complete eigensolution is either unnecessary or computer‐timeconsuming and inaccurate for higher modes; in finite‐element modelling only lower‐order Ritz vectors or even static deformation modes in normal cases are employed.
Computational efficiency of p‐ and h‐ version elements
Authors: Gupta Ajaya Kumar , Fang Ting‐Hsiung , Chen Hong 
Published: August 2005

AbstractThe plate‐with‐a‐circular‐hole problem has been solved using p‐ and h‐version models. Both models give solutions of comparable accuracy in roughly the same amount of computer time. As p is increased from 8 to 10 in the p‐version models, and the number of 8‐node isoparametric elements is increased from 30 to 42 in h‐version models, the accuracy of stress values and distributions does not improve significantly in both versions. However, the computational effort in the p‐version models increases much more (200%) than it does in the h‐version models (40%). Because one of the edges in each of the two elements of the p‐version model is curved, the stiffness matrix cannot be evaluated in closed form and consumes a significant amount of computer time.
Extension and application of the QUICKER scheme to a non‐uniform rectangular grid system
Authors: Koo Hyeong‐Mo , Park Seung O. 
Published: August 2005

AbstractThe QUICKER formulation of the QUICK scheme is extended to a non‐uniform rectangular grid system that can be widely adopted for the calculation of the flow problems of engineering interest. This new formulation is applied to obtain solutions of a one‐dimensional non‐linear Burgers equation and a two‐dimensional lid‐driven cavity flow. The computational results show that the new formulation is superior to existing schemes such as hybrid and skew‐upwind‐differencing, especially when the grid Peclet (or Reynolds) number is high.
A parallel transient algorithm for structures with extended independent substructure computation
Authors: Bennighof Jeffrey K. , Wu Jiann‐Yuarn 
Published: August 2005

AbstractA parallel algorithm for linear structure transient response problems is presented in which transient response is computed independently for substructures for extended periods of time, and these substructure responses are then corrected to obtain the response of the overall coupled structure. The correction of the uncoupled substructure responses only requires the interface portions of these responses sampled occasionally in time, and is done independently for different substructures in a streamlined procedure. A numerical example is presented to demonstrate the method and show its accuracy.
Geometrically non‐linear analysis of shell structures
Authors: Moy S. S. J. , Lam S. S. E. 
Published: August 2005

AbstractThe paper presents a finite element formulation for the geometrically non‐linear analysis of shells. The formulation is based on the Hellinger—Reissner approach and uses internal transverse shear stress unknowns to alleviate the problem of shear locking. A ring and a quadrilateral element are presented, together with three examples which demonstrate the accuracy of the elements.
Hierarchical hybrid rectangular finite‐element formulation for 2‐D elasticity problems
Authors: Perry B. , Bar‐Yoseph P. , Rosenhouse G. 
Published: August 2005

AbstractA simple and efficient algorithm for the generation of hierarchical hybrid rectangular finite elements for two‐dimensional elasticity problems is presented. A significant saving in computational effort needed for calculating the stiffness matrices of the various finite elements is gained by using symbolic algebra for calculating exactly the necessary integrals. Hierarchical matrices G and H, corresponding to a stress field up to a cubic approximation and a displacement field up to a quadratic approximation, are detailed. The described method for generating hierarchical hybrid stress elements could easily be extended for higher‐order elements.
Quadrilateral isoparametric finite element with central node
Authors: Stefanov Ivo 
Published: August 2005

AbstractThe quadrilateral four‐node isoparametric finite element is transformed by adding a fifth node in its centre. The shape functions used are of relatively high degree and satisfy the requirements for compatibility and completeness. In the numerical examples the new five‐node finite element provides a better accuracy than the classic four‐node one.
Non‐linear terms in frame analysis using eulerian moving co‐ordinates
Authors: El‐Ghazaly Hany Ahmed 
Published: August 2005

AbstractThe effect of retaining the non‐linear term (½ u) in the strain‐displacement equations for frame analysis using Eulerian moving co‐ordinates is discussed. The resulting non‐linear equilibrium equations are solved using the energy search method of analysis. Two examples are discussed involving tension‐bending and compression‐bending coupling. It has been shown that the non‐linear term (½ u) may be omitted from the strain‐displacement relationship without sacrificing any significant accuracy. The finding agrees in substance with a conclusion reported in the literature which was limited to non‐linear stability analysis of truss structures.
Variational principles and hybrid approach for finite deformation analysis of shells
Authors: Qin Q. H. , Jin F. S. 
Published: August 2005

AbstractA complementary Hu‐Washizu functional Γ3, based on formulae presented by Atluri (1984), is given in dyadic notation. By introducing Legendre transformation, the Heillinger‐Reissner functional Π2, Γ2 and the classic potential energy functional Π1 are obtained. An incremental modelling of functional Γ3 for the analysis of finite deformation and finite rotations of arbitrarily shaped shells is presented. The numerical results are shown to be in good agreement with those found in published literature.
A general computational method for solving non‐linear free boundary‐value problems of plane hydrodynamics
Authors: Moussa Nabil 
Published: August 2005

AbstractThis work is based on the constructive existence proof of solutions of a comprehensive class of non‐linear free boundary‐value problems of plane hydrodynamics by E. Zeidler (1971). A general computational method was developed and illustrated on the specific case of permanent heavy waves in infinite channels.
A compact unconditionally stable finite‐difference method for transient one‐dimensional advection‐diffusion
Authors: Noye B. J. 
Published: August 2005

AbstractA new compact second‐order finite‐difference method for solving the time‐dependent one‐dimensional constant‐coefficient advection—diffusion equation is developed. It involves a spread of only two grid points in space and two levels in time. It may be evaluated in an explicit marching manner and requires the availability of only upstream boundary values. It is unconditionally stable and has the property of giving ‘non‐negative’ values for a large range of Courant and diffusion numbers. For all grid Reynolds numbers greater than 2 it is shown to be more accurate than commonly used second‐order methods, all of which involve a spread of three grid points in space.
Axisymmetric potential flow calculations. Part 2: Design mode
Authors: Zhang S. , Barron R. M. , Rudraiah N. 
Published: August 2005

AbstractThe pure inverse problem of designing a body with a prescribed surface pressure in incompressible axisymmetric potential flow is solved using the streamfunction as a co‐ordinate in the computational plane. The problem is formulated mathematically as a mixed boundary value problem and the solution is obtained using the finite‐difference technique. The body shape is computed simultaneously with the entire flow field and does not have to be iteratively adjusted to meet the target surface pressure. Results are presented for elliptical, NACA 0012 and minimum‐drag cross‐sections.