bluuebunny/crossref_metadata_2025_split huggingface dataset:
The use of small‐format and low‐altitude aerial photos for the realization of high‐resolution DEMs in mountainous areas: application to the Super‐Sauze earthflow (Alpes‐de‐Haute‐Provence, France)
Authors: Henry J.‐B. , Malet J.‐P. , Maquaire O. , Grussenmeyer P. 
Published: November 2002

AbstractGeomorphologists have to make choices and compromises, as acquisition techniques of geometrical information are numerous, depending on the specific complexity of the targeted three‐dimensional objects and the requirements of the end user. This article presents the methodology and the results over a well known and documented site. This ready‐to‐use, low‐altitude, aerial photo methodology reveals itself to be a satisfying compromise between cost, accuracy and difficulty of implementation. The selected equipment package is light enough to enable a quick reaction to unexpected events and the tools and methods are competitive with field acquisition techniques. An evaluation has demonstrated a sub‐metric accuracy for the final result. Copyright © 2002 John Wiley & Sons, Ltd.
The use of a landscape simulator in the validation of the SIBERIA landscape evolution model: transient landforms
Authors: Hancock G. R. , Willgoose G. R. 
Published: November 2002

AbstractSIBERIA is a physically based model for the geomorphic evolution of landforms. It is essential that the SIBERIA model be tested or validated against controlled landform development. Previous studies have demonstrated that SIBERIA is able to simulate declining equilibrium landforms and in this paper we examine SIBERIA's ability to simulate landforms as they evolve to their declining equilibrium form. These landscapes are termed transient landforms. Landscapes generated by SIBERIA were compared to those produced by a physical model (experimental model landforms) at stages of evolution. Comparison of the experimental landscapes with the simulated landscapes using total mass, hypsometric curve, width function, cumulative area distribution and area–slope demonstrate that SIBERIA can simulate the experimental model landscape during development (i.e. transient landscapes). Copyright © 2002 John Wiley & Sons, Ltd.
Extension of a combined analytical/numerical initial value problem solver for unsteady periodic flow
Authors: De Chant Lawrence J. , Seidel Jonathan A. , Kline Teresa R. 
Published: November 2002

AbstractHere we describe analytical and numerical modifications that extend the Differential Reduced Ejector/ mixer Analysis (DREA), a combined analytical/numerical, multiple species ejector/mixing code developed for preliminary design applications, to apply to periodic unsteady flow. An unsteady periodic flow modelling capability opens a range of pertinent simulation problems including pulse detonation engines (PDE), internal combustion engine ICE applications, mixing enhancement and more fundamental fluid dynamic unsteadiness, e.g. fan instability/vortex shedding problems. Although mapping between steady and periodic forms for a scalar equation is a classical problem in applied mathematics, we will show that extension to systems of equations and, moreover, problems with complex initial conditions are more challenging. Additionally, the inherent large gradient initial condition singularities that are characteristic of mixing flows and that have greatly influenced the DREA code formulation, place considerable limitations on the use of numerical solution methods. Fortunately, using the combined analytical–numerical form of the DREA formulation, a successful formulation is developed and described. Comparison of this method with experimental measurements for jet flows with excitation shows reasonable agreement with the simulation. Other flow fields are presented to demonstrate the capabilities of the model. As such, we demonstrate that unsteady periodic effects can be included within the simple, efficient, coarse grid DREA implementation that has been the original intent of the DREA development effort, namely, to provide a viable tool where more complex and expensive models are inappropriate. Copyright © 2002 John Wiley & Sons, Ltd.
A Petrov–Galerkin method for flows in cavities: enclosure of aspect ratio 8
Authors: Suslov Sergey A. , Paolucci Samuel 
Published: November 2002

AbstractA Petrov–Galerkin method for computations of fully enclosed flows is developed. It makes use of divergence‐free basis functions which also satisfy the boundary conditions for the velocity field. This allows the elimination of the unknown pressure. The computational procedure reduces to the solution of a system of non‐linear first‐order ordinary differential equations for the spectral expansion coefficients. We illustrate the effectiveness and accuracy of the method by solving the problem of the two‐dimensional thermoconvective flow in a rectangular cavity of aspect ratio 8 at Rayleigh number 3.4×105. Copyright © 2002 John Wiley & Sons, Ltd.
Unsteady natural convection in tall side‐heated cavities
Authors: Armfield S. , Schultz A. 
Published: November 2002

AbstractA finite‐volume scheme is used to simulate super‐critical natural convection flow in a side‐heated cavity with height/width aspect ratio of eight. The flow is unsteady with travelling waves circulating around the cavity in the flow direction. Results on a range of grids with QUICK and central difference advection discretizations show that a very fine grid is required to ensure a converged solution is obtained. A linear parallel stability analysis has been carried out and it is shown that the basic wave structure of the flow is well predicted. Copyright © 2002 John Wiley & Sons, Ltd.
An operator‐splitting finite‐element approach to the 8:1 thermal‐cavity problem
Authors: Davis D. , Bänsch E. 
Published: November 2002

AbstractThis article describes the methodology for, and results obtained from, our contribution to the thermal‐cavity benchmark test. Our solutions were obtained on graded rectangular grids for two different time‐discretization schemes by applying a finite‐element procedure to the model equations, and a combination of conjugate‐gradient and GMRES solvers to the resulting matrix systems. Copyright © 2002 John Wiley & Sons, Ltd.
Fourth‐order finite difference simulation of a differentially heated cavity
Authors: Johnston Hans , Krasny Robert 
Published: November 2002

AbstractWe present benchmark simulations for the 8: 1 differentially heated cavity problem, the focus of a special session at the first MIT conference on Computational Fluid and Solid Mechanics in June 2001. The numerical scheme is a fourth‐order finite difference method based on the vorticity‐stream function formulation of the Boussinesq equations. The momentum equation is discretized by a compact scheme with the no‐slip boundary condition enforced using a local vorticity boundary condition. Long‐stencil discretizations are used for the temperature transport equation with one‐sided extrapolation applied near the boundary. The time stepping scheme for both equations is classical fourth‐order Runge–Kutta. The main step is the solution of two discrete Poisson‐like equations at each Runge–Kutta time stage, which are solved using FFT‐based methods. Copyright © 2002 John Wiley & Sons, Ltd.
Numerical prediction of natural convection in a tall enclosure
Authors: Christopher David M. 
Published: November 2002

AbstractThe equations for natural convection flow in a tall cavity were solved for a super‐critical Rayleigh number for which oscillations occur in the flow field and various solutions are possible. The objective was to compare various solution methods for this complex flow situation. The equations were solved using the finite element method with the Galerkin form of the method of weighted residuals with various time integration methods, time steps and grid spacings. The Euler time integration method is unsuitable for this problem because of its excessive dissipation. Fine grid distributions and small time steps were needed to predict accurate values of the average temperatures and velocities in the cavity, with even finer elements and time steps needed to accurately predict the amplitudes of the oscillations. An initially uniform temperature distribution lead to a uniformly oscillating skew‐symmetric flow field. An initially random temperature field lead to a symmetry‐breaking flow field that eventually reached the skew‐symmetric flow field after a long time. Copyright © 2002 John Wiley & Sons, Ltd.
A numerical study of a natural convection flow in a cavity
Authors: Guo Yanhu , Bathe Klaus‐Jürgen 
Published: November 2002

AbstractThe solution to a benchmark problem of a differentially heated cavity flow with Ra=3.4×105 and Pr=0.71 was solicited for presentation at a special session entitled ‘Computational Predictability of Natural Convection Flows in Enclosures’ which was held at the First MIT Conference on Computational Fluid and Solid Mechanics. The objective of this paper is to present the results obtained using the ADINA System.The 9‐node quadrilateral element in ADINA was used with various meshes. Periodic solutions with a period of 3.42–3.43 were obtained. Compared with the average values of the solution variables and the periods, the calculated amplitudes of the periodic solutions were found to be more sensitive to the spatial and temporal discretizations used. The flow patterns, such as boundary layers, vortices, etc. were also studied using a fine 40×120 element mesh. Vortices and their evolutions were revealed inside the periodic flow field. Copyright © 2002 John Wiley & Sons, Ltd.
Computational predictability of time‐dependent natural convection flows in enclosures (including a benchmark solution)
Authors: Christon Mark A. , Gresho Philip M. , Sutton Steven B. 
Published: November 2002

AbstractThis paper summarizes the results from a special session dedicated to understanding the fluid dynamics of the 8:1 thermally driven cavity which was held at the First MIT Conference on Computational Fluid and Solid Dynamics in June, 2001. The primary objectives for the special session were to: (1) determine the most accurate estimate of the critical Rayleigh number above which the flow is unsteady, (2) identify the correct, i.e. best time‐dependent benchmark solution for the 8: 1 differentially heated cavity at particular values of the Rayleigh and Prandtl numbers, and (3) identify those methods that can reliably provide these results. Copyright © 2002 John Wiley & Sons, Ltd.
From steady to chaotic solutions in a differentially heated cavity of aspect ratio 8
Authors: Bruneau Charles‐Henri , Saad Mazen 
Published: November 2002

AbstractA splitting method is used for the temperature and the velocity–pressure unknowns to solve the time‐dependent thermal convection problem in an 8:1 enclosure (International Journal for Numerical Methods, this issue). High performance is obtained by means of incomplete Cholesky conjugate gradient for the temperature equation on one hand and a multigrid procedure for Navier–Stokes equations on the other hand. The approximation is achieved by second‐ and third‐order finite differences on staggered grids. The stability of the steady solution is analysed by the computation of the first Lyapunov exponent. The periodic flow at Ra=3.4×105 is widely discussed and some investigations have been done for some higher Rayleigh numbers. Copyright © 2002 John Wiley & Sons, Ltd.
Fully coupled and operator‐splitting approaches for natural convection flows in enclosures
Authors: Turek S. , Schmachtel R. 
Published: November 2002

AbstractWe present two different numerical approaches for the simulation of incompressible flow with heat transfer which is described via the Boussinesq model. Exemplarily, we describe a fully coupled approach, which allows both non‐steady and steady simulations, while the decoupled approach is based on operator‐splitting techniques as typical for fully non‐steady incompressible problems. We discuss the numerical and computational characteristics and show results for the MIT2001 benchmark. All results are based on the Open Source CFD tool FEATFLOW (see www.featflow.de). Copyright © 2002 John Wiley & Sons, Ltd.
Numerical investigation of the first instabilities in the differentially heated 8:1 cavity
Authors: Auteri F. , Parolini N. 
Published: November 2002

AbstractWe present a new Galerkin–Legendre spectral projection solver for the simulation of natural convection in a differentially heated cavity. The projection method is applied to the study of the first non‐stationary instabilities of the flow in a 8:1 cavity. Statistics of the periodic solution are reported for a Rayleigh number of 3.4×105. Moreover, we investigate the location and properties of the first Hopf bifurcation and of the three successive bifurcations. The results confirm the previous finding in the range of Rayleigh numbers investigated that the flow instabilities originate in the boundary layer on the vertical walls. A peculiar phenomenon of symmetry breaking and symmetry restoring is observed portraying the first steps of the transition to chaos for this flow. Copyright © 2002 John Wiley & Sons, Ltd.
An extended Chebyshev pseudo‐spectral benchmark for the 8:1 differentially heated cavity
Authors: Xin Shihe , Quéré Patrick Le 
Published: November 2002

AbstractOur contribution to the benchmark is multifold. In addition to providing accurate unsteady simulations at the required Ra value of 3.4 × 105, we determine accurately the three first critical bifurcation points, investigate the supercritical regime, and study the differences between time‐averaged solutions and the corresponding base solution at Ra = 4× 105. We thereby establish the existence of, at least, 4 different branches of solutions and of 3 multiple unsteady periodic solutions for a Rayleigh value of 4 × 105. First appearance of quasi‐periodic flow is found at Ra about 5.0 × 105 and first appearance of chaotic solutions is found for 5.5 × 105 approximately. We investigate the differences between time‐averaged solutions and the corresponding base flow solution at Ra = 4 × 105. It is found that they exhibit symmetric feature and similar spatial distribution and that their amplitudes are proportional to the squared amplitude of periodic solutions.All these computations are carried out using 2D Chebyshev spatial approximations with spatial resolution up to 48 × 180. For the unsteady computations, a second order time stepping scheme is used, the incompressibility condition being strictly enforced through the use of an influence matrix technique, while for the accurate determination of the critical points, an original algorithm based on a combination of Newton, continuation and Arnoldi Krylov type methods was developed.Furthermore we investigate the stability of the 2D benchmark solution with respect to 3D periodic disturbances by using a spectral (Chebyshev and Fourier) time‐stepping (projection) code. In the 8:1 cavity we did not find any 3D instability before the onset of time dependence of 2D flows nor at the mandatory Ra of 3.4 × 105. 3D instabilities were observed for Ra about 4× 105 corresponding to a typical wavelength of two times the cavity width. Copyright © 2002 John Wiley & Sons, Ltd.
LS‐DYNA and the 8:1 differentially heated cavity
Authors: Christon Mark A. 
Published: November 2002

AbstractThis paper presents results computed using LS‐DYNA's new incompressible flow solver for a differentially heated cavity with an 8:1 aspect ratio at a slightly super‐critical Rayleigh number. Three Galerkin‐based solution methods are applied to the 8:1 thermal cavity on a sequence of four grids. The solution methods include an explicit time‐integration algorithm and two second‐order projection methods—one semi‐implicit and the other fully implicit. A series of ad hoc modifications to the basic Galerkin finite element method are shown to result in degraded solution quality with the most serious effects introduced by row‐sum lumping the mass matrix. The inferior accuracy of a lumped mass matrix relative to a consistent mass matrix is demonstrated with the explicit algorithm which fails to obtain a transient solution on the coarsest grid and exhibits a general trend to under‐predict oscillation amplitudes. The best results are obtained with semi‐implicit and fully implicit second‐order projection methods where the fully implicit method is used in conjunction with a ‘smart’ time integrator. Copyright © 2002 John Wiley & Sons, Ltd.
Weighted average flux method and flux limiters for the numerical simulation of shock waves in rigid porous media
Authors: Torrens R. , Wrobel L. C. 
Published: November 2002

AbstractThe one‐dimensional flow field generated by the passage of a shock wave in a rigid, thermoelastic porous foam has been simulated using a two‐phase mathematical model. The work presented here makes use of the weighted average flux method to solve the system of six equations that govern the problem. Spurious oscillations are eliminated through the application of total variation diminishing limiting methods. Four different limiters were tested: van Leer, SuperA, MinA and van Albada. Numerical tests were carried out to verify the performance of each flux limiter in terms of accuracy. The results were compared to analytical and previously obtained data to assess the performance of the mathematical model. Excellent agreement was obtained. Copyright © 2002 John Wiley & Sons, Ltd.
A Mach‐uniform unstructured staggered grid method
Authors: Wenneker I. , Segal A. , Wesseling P. 
Published: November 2002

AbstractA novel Mach‐uniform method to compute flows using unstructured staggered grids is discussed. The Mach‐uniform method is a generalization of the pressure‐correction approach for incompressible flows, and is valid for Mach numbers ranging from 0 (incompressible) to > 1 (supersonic). The primary variables (ρu,p and ρ) are updated sequentially. The grid consists of triangles. A staggered positioning of the variables is employed: the scalar variables are located at the centroids of the triangles, whereas the normal momentum components are positioned at the midpoints of the faces of the triangles. Discretization of the two‐dimensional flow equations on unstructured staggered grids is discussed. For the cell face fluxes there is a choice between first‐order upwind and central approximation. Flows around the NACA 0012 airfoil with freestream Mach numbers ranging from 0 to 1.2 are computed to demonstrate the Mach‐uniform accuracy and efficiency of the proposed method. Copyright © 2002 John Wiley & Sons, Ltd.
Extending the temporal and spatial limits of gentrification: a research agenda for population geographers
Authors: Smith Darren P. 
Published: November 2002

AbstractHow processes of gentrification unfold, at what rate, and with what effects, can all differ substantially in different places. Although pre‐existing theories have sought to encapsulate this diversity, the temporal and spatial limits of gentrification processes have yet to be fully explored. This paper postulates that population geographers have a role to play here. Firstly, researchers are urged to study gentrification within a broader temporal perspective, and to unravel connections between migration dynamics and population transitions over the course of the process. Secondly, it is contended that processes and effects of gentrification should be examined within wider spatial frameworks, whereby migration flows of relatively affluent households are evaluated within the context of (re)urbanisation, suburbanisation and counterurbanisation. This may pose important questions about the understandings of demographic links between gentrification and in‐migrants at particular stages of their life‐course. It is argued that this research agenda will require the adoption of more inclusive definitions of gentrification, embracing wider spatial and temporal criteria. Copyright © 2002 John Wiley & Sons, Ltd.
A geographical analysis of spatial differentials in mobility and self‐care limitations among older Americans
Authors: Lin Ge , Zimmer Zachary 
Published: November 2002

AbstractIn this article we examine regional variations in functional limitations of older Americans. We consider models for ‘life‐long residents’ or those who currently live in their region of birth, and ‘secondary residents’ or those who live in a different region. Sizeable differences in limitations exist, with a higher rate in southern regions. Using a multinomial logit model, we further assess the geographical disparities in functional status while controlling for socioeconomic status (SES) and other characteristics. We conclude that the regional differentials are persistent. Those who have moved away from the south carry a burden of functional limitation with them wherever they go. Simulations based on estimated models suggest that improving individual SES can substantially increase the disability‐free life span, but it cannot completely negate geographical influences. Copyright © 2002 John Wiley & Sons, Ltd.
Labour‐market participation of Asian Indian immigrant women in the greater Kansas City Metropolitan Area, USA
Authors: De Dunn Sujata , Paul Bimal Kanti 
Published: November 2002

AbstractImmigrants are changing the composition of the American population at the end of the twentieth and into this century, just as they have done for many decades. The amended Immigration and Naturalization Act of 1965 resulted in a steady flow of professional Asian Indians to the United States. While receiving indirect attention in several studies, relatively little is known about the labour‐market participation of Asian Indian immigrant women. This research aims to determine the economic and non‐economic factors that influence the participation of Asian Indian immigrant women in the labour market of the Greater Kansas City Metropolitan Area. On the basis of 160 responses from a questionnaire survey, this research found that annual income, years in current job, occupation type, and the nature of investment in India were the pertinent economic factors, while non‐economic factors range from age, urban residential background, education, number of years in the US, the decision to work, and some perceptions on work, homemaking and household income contribution. Findings from this study are discussed in the context of existing theories on international migration, particularly those dealing with the labour‐force participation of immigrants. Copyright © 2002 John Wiley & Sons, Ltd.
Mothers' insightfulness regarding their children's internal worlds: The capacity underlying secure child–mother relationships
Authors: Oppenheim David , Koren‐Karie Nina 
Published: November 2002

AbstractThis article introduces a new method to assess mothers' insightfulness regarding their children's inner world. Maternal insightfulness involves the capacity to see things from the child's point of view, and is based on insight into the child's motives, a complex view of the child, and openness to new information about the child. Insightfulness is seen as the capacity underlying positive parenting and providing the context for secure child–parent attachment. In the assessment of insightfulness mothers view video segments of their interactions with their children and are subsequently interviewed regarding their children's and their own thoughts and feelings during the segments. This article describes how the maternal interviews are coded and provides vignettes of both insightful and noninsightful mothers. Empirical findings supporting the validity of the insightfulness assessment are reviewed, and the implications for children's development are discussed. ©2002 Michigan Association for Infant Mental Health.