bluuebunny/crossref_metadata_2025_split huggingface dataset:
Turbulent heat transfer via the F.E.M.: Heat transfer in rod bundles
Authors: Taylor C. , Thomas C. E. , Morgan K. 
Published: August 2005

AbstractHeat transfer associated with forced convection between bundles of cylindrical fuel rods is analysed using the finite element method. A subchannel technique is employed and the numerical results are compared with previous experimental and numerical values. The solid and fluid zones are analysed, for temperature distribution, as a single domain.
An ‘assumed deviatoric stress–pressure–velocity’ mixed finite element method for unsteady, convective, incompressible viscous flow: Part I: Theoretical development
Authors: Yang Chien‐Tung , Atluri Satya N. 
Published: August 2005

AbstractA formulation of a mixed finite element method for the analysis of unsteady, convective, incompressible viscous flow is presented in which: (i) the deviatoric‐stress, pressure, and velocity are discretized in each element, (ii) the deviatoric stress and pressure are subject to the constraint of the homogeneous momentum balance condition in each element, a priori, (iii) the convective acceleration is treated by the conventional Galerkin approach, (iv) the finite element system of equations involves only the constant term of the pressure field (which can otherwise be an arbitrary polynomial) in each element, in addition to the nodal velocities, and (v) all integrations are performed by the necessary order quadrature rules. A fundamental analysis of the stability of the numerical scheme is presented. The method is easily applicable to 3‐dimensional problems. However, solutions to several problems of 2‐dimensional Navier‐Stokes' flow, and their comparisons with available solutions in terms of accuracy and efficiency, are discussed in detail in Part II of this paper.
Free surface wave motions and interactions
Authors: Miner E. W. , Fritts M. J. , Griffin O. M. , Ramberg S. E. 
Published: August 2005

AbstractThis paper investigates the problems involved in the numerical simulation of free surface wave motions and surface wave effects on marine structures. Various approaches that might be taken in meeting these problems are discussed, and their relative advantages and disadvantages are considered. One particular approach combines a Lagrangian formulation of the governing equations, a triangular grid and a finite‐difference solution procedure. Since this approach has some distinct advantages in the numerical calculation of fluid flows which include a free surface, it formed the basis for the development of one particular computer code, SPLISH. Sufficient progress has been made with the SPLISH code to demonstrate the attractiveness of numerical calculations for wave flow problems. Recent computational results demonstrate that realistic time‐varying local flow fields, pressures and forces on and near structures such as a half‐cyclinder on the ocean floor can be determined from numerical calculations for certain conditions. Good agreement is found in comparison of the numerical results from SPLISH, recent linear wave Green's function and fifth‐order asymptotic solutions for wave motion over a bottom seated half‐cylinder, and an experimental simulation in a wave channel.
A transient finite element analysis of natural convection around a horizontal hot cylinder
Authors: Miyauchi Yasuyuki , Masuda Michio , Shimizu Masatsugu 
Published: August 2005

AbstractThis paper presents an advanced method for a 2‐dimensional analysis of transient natural convection by finite element method. The present method, based on stream function—vorticity formulation, could get rid of numerical errors and constraint of perpendicular mesh subdivision, since we excluded a finite difference approximation of vorticity on no‐slip boundaries. A considerable effect of upwind weighting function was examined. The method was successfully applied to a problem of natural convection around a horizontal hot cylinder.
A modified dodge algorithm for the parabolized Navier–Stokes equations and compressible duct flows
Authors: Cooke C. H. , Dwoyer Douglas M. 
Published: August 2005

AbstractA revised version of Dodge's split‐velocity method for numerical calculation of compressible duct flow has been developed. The revision incorporates balancing of mass flow rates on each marching step in order to maintain front‐to‐back continuity during the calculation. The (chequerboard) zebra algorithm is applied to solution of the three‐dimensional continuity equation in conservative form. A second‐order A‐stable linear multistep method is employed in effecting a marching solution of the parabolized momentum equations. A chequerboard iteration is ued to solve the resulting implicit non‐linear systems of finite‐difference equations which govern stepwise transition. Qualitive agreement with analytical predictions and experimental results has been obtained for some flows with well‐known solutions.
A multi‐vortex model of leading‐edge vortex flows
Authors: Peace A. J. 
Published: August 2005

AbstractA multi‐vortex model of the vortex sheets shed from the sharp leading edges of slender wings is considered. The method, which is developed within the framework of slender‐body theory, is designed to deal with those situations in which more than one centre of rotation is formed on the wing, for example on a slender wing with lengthwise camber or with a strake. Numerical results are presented, firstly for situations where comparison can be made with a vortex sheet model and secondly for cases, such as those described above, where a vortex sheet model is unable to describe the flow. Where comparison is available, agreement is good and in the cases where more than one vortex system is present interesting interactions are obtained.
Fractional step algorithm for estuarine mass transport
Authors: Sobey R. J. 
Published: August 2005

AbstractA successful and economical fractional step algorithm for the convection‐dispersion‐reaction equation is described. Exact solutions are adopted for the reaction and convection steps, the latter by the introduction of a moving co‐ordinate system. The dispersion step uses an optimized finite difference algorithm which specifically accommodates the grid non‐uniformity. The excellent performance of the algorithm is confirmed by numerical experiments together with computations of the Fourier response and integrated square error characteristics.
Application of a high accuracy finite difference technique to steady, free surface flow problems
Authors: Chapman Raymond S. , Kuo Chin Y. 
Published: August 2005

AbstractThe spatially third‐order accurate QUICK finite difference technique is applied to the solution of the depth‐integrated equations of motion for steady, subcritical, free surface flow in a wide, shallow, rectangular channel with and without an abrupt expansion. The conservative, control‐volume discretization of the equations of motion and the use of QUICK in approximating required cell and cell face average quantities is discussed. Results presented show that it is possible to obtain stable solutions for advective free surface flows without resorting to implicit numerical smoothing.
Numerical modelling of wind flow over buildings in two dimensions
Authors: Hanson T. , Summers D. M. , Wilson C. B. 
Published: August 2005

AbstractNumerical solutions to the Navier–Stokes equation may provide designers with predictions of the wind environment of buildings under design. To investigate this possibility, two complementary solution procedures are implemented for two‐dimensional geometry: a random vortex method to depict the flow evolution, and a control volume method to depict the steady flow field. These are both illustrated by specific application to the case of a building form with a roof of arbitrary pitch.
Selective lumping finite element method for nearshore current
Authors: Kawahara Mutsuto , Kashiyama Kazuo 
Published: August 2005

AbstractA finite element method for the analysis of nearshore current, which is one of the principal currents in coastal seas, is presented in this paper. Because the nearshore current is induced by the variable distribution of the surface waves, it is necessary to analyse two main characteristics of the wave, i.e. direction and height. The current can be computed using the resulting wave characteristics. The present method makes it possible to employ procedures for which the same methods of solution are applicable for all basic equations of wave direction, height and current flow. The linear interpolation function is used for the discretization of spatial variables and a selective lumping two step explicit scheme is employed for the numerical integration in time. The numerical solutions obtained are compared with analytical, experimental and observed ones. From these comparative studies, it is concluded that the present finite element method provide a useful tool for the analysis of nearshore current.
Simulations of flows and water depth in a dendritic river system
Authors: Yeh G. T. 
Published: August 2005

AbstractThis paper presents the development of a channel hydrodynamic model for simulating the behaviour of flows and water depths in a river network that may consist of any number of joined and branched rivers/streams, including both tidal and non‐tidal rivers. The model employs a numerical method—an integrated compartment method (ICM). The method greatly facilitates the set‐up of algebraic equations for the discrete field approximating the corresponding continuous field.Most of the possible boundary conditions that may be anticipated in real‐world problems are considered. These include junctions, prescribed flow, prescribed water depth (or cross‐sectional area), and rating curve boundaries. The use of ICM makes the implementation of these four types of boundary conditions relatively easy.The model is applied to two case studies: first to a single river and then to a network of five river branches in a watershed. Results indicate that the model can simulate the behaviour of the hydrodynamic variables that are required to compute chemical transport in a river‐stream network.
A finite element method to solve the Navier‐Stokes equations using the method of characteristics
Authors: Huffenus J. P. , Khaletzky D. 
Published: August 2005

AbstractWe present a simple and efficient finite element method to solve the Navier‐Stokes equations in primitive variables V, p. It uses (a) an explicit advection step, by upwind differencing. Improvement with regard to the classical upwind differencing scheme of the first order is realized by accurate calculation of the characteristic curve across several elements, and higher order interpolation; (b) an implicit diffusion step, avoiding any theoretical limitation on the time increment, and (c) determination of the pressure field by solving the Poisson equation. Two laminar flow calculations are presented and compared to available numerical and experimental results.
A collocation method for convection dominated flows
Authors: Chawla T. C. , Leaf G. , Minkowycz W. J. 
Published: August 2005

AbstractA collocation method based on multiple regions with moving boundaries placed in a flow field in which convection effects dominate, is proposed. By making the moving boundaries of the regions coincide with moving sharp fronts present in the solution of convection dominated problems, and thereby allowing higher concentration of meshes to be placed about the fronts, the proposed method is able to achieve very high accuracy. By having a moving mesh, the Peclet number characterizing the flow field depends upon velocity relative to a moving mesh in a region. Consequently by choosing proper velocities of the moving boundaries, the value of this Peclet number can be made as small as desired. The traditional collocation method based on centred discretization, when applied to each region in the field, produces oscillation free solutions even when the values of Peclet number based on absolute velocity are extremely large. In view of these characteristics the method appears to be an excellent candidate for the solution of any two‐phase flow problem containing sharp fronts.
On the accuracy of boundary fitted finite‐difference calculations
Authors: Ferreri J. C. , Ventura M. A. 
Published: August 2005

AbstractA description is given of the effects of the discretization of the domain of integration on the accuracy of the results obtained with boundary‐fitted finite differences. Three‐dimensional unsteady heat conduction problems and two dimensional Navier‐Stokes equations are considered. Comparisons with analytic solutions are given for all cases. It is shown that grid shapes influence the accuracy of the results and quantitative error evaluations are provided for some interesting cases.
Elasto‐hydrodynamic lubrication: A non‐linear complementarity problem
Authors: Kostreva Michael M. 
Published: August 2005

AbstractThe classical problem of elasto‐hydrodynamic lubrication of cylinders in line contact is formulated as a non‐linear complementarity problem. A direct algorithm is applied to the approximation obtained by finite differences. Implementation considerations are emphasized. The new method provides reliable and automatic location of the previously troublesome lubricant free boundary. Numerical results reveal the qualitative behaviour of the pressure distribution and the lubricant film thickness under variation of key physical parameters.
A modified finite element method for solving the time‐dependent, incompressible Navier‐Stokes equations. Part 1: Theory
Authors: Gresho Philip M. , Chan Stevens T. , Lee Robert L. , Upson Craig D. 
Published: August 2005

AbstractBeginning with the Galerkin finite element method and the simplest appropriate isoparametric element for modelling the Navier‐Stokes equations, the spatial approximation is modified in two ways in the interest of cost‐effectiveness: the mass matrix is ‘lumped’ and all coefficient matrices are generated via 1‐point quadrature. After appending an hour‐glass correction term to the diffusion matrices, the modified semi‐discretized equations are integrated in time using the forward (explicit) Euler method in a special way to compensate for that portion of the time truncation error which is intolerable for advection‐dominated flows. The scheme is completed by the introduction of a subcycling strategy that permits less frequent updates of the pressure field with little loss of accuracy. These techniques are described and analysed in some detail, and in Part 2 (Applications), the resulting code is demonstrated on three sample problems: steady flow in a lid‐driven cavity at Re ≤ 10,000, flow past a circular cylinder at Re ≤ 400, and the simulation of a heavy gas release over complex topography.
Two‐step explicit finite element method for two‐layer flow analysis
Authors: Kasahara Koichi , Hara Heihachiro , Kawahara Mutsuto 
Published: August 2005

AbstractA finite element method for the analysis of two‐layer density flows is presented in this paper. The standard Galerkin method based on linear interpolation functions is used to yield discrete spatial variables. For numerical integration in time, an explicit two‐step selective lumping method is used. Here it is applied to a flow analysis of Ishikari Bay, at the mouth of Ishikari River. This case demonstrates a procedure that yields a numerically stable solution.
Numerical computation of transient shocked chemically reactive flows
Authors: Rajan S. 
Published: August 2005

AbstractUsing the ability of the method of characteristics to evaluate shock fronts in an accurate manner, a formulation is presented which incorporates the effect of rapid exothermic chemical reactions in the flow. The formulation is applied to the computation of the unsteady reactive flow field behind a cylindrial expanding blast wave propagating in a mixture of hydrogen and oxygen. Details of the computational procedure are described. Results are presented for a sample problem and compared with those for the non‐reactive case to illustrate the influence of chemical reactions.
Stability of flow over a rotating disk
Authors: Szeri A. Z. , Giron A. 
Published: August 2005

AbstractThe perturbation equations which characterize the stability of flow over a rotating infinite disk are derived via strict order of magnitude analysis. These equations contain viscous terms not considered by Stuart,1 curvature and Coriolis terms not considered by Brown,2 and axial velocity terms not considered by Kobayashi et al.3 The strategy for reducing the problem to an algebraic system is Galerkin's method with B‐spline discretization. In comparison with the Poiseuille flow solutions of Orszag,4 the method is shown to perform well without placing undue demands on computing capability. Critical values of Reynolds number, wave length, vortex orientation and number of spiral vortices calculated by the present method compare favourably with experimental data of Kobayashi et al.
A finite element for incompressible plane flows of fluids with memory
Authors: Bernstein Barry , Malkus David S. , Olsen Elwood T. 
Published: August 2005

AbstractFlows of fluids with single‐integral memory functionals are considered. Evaluation of the stress at a material point involves the deformation history of that point, and a dominant computational cost in finite element approximation is the construction of streamlines. It is shown that the simple crossed‐triangle macro‐element is in many ways an ideal finite element for the difficult non‐linear, non‐self‐adjoint problem. The question as to whether this element produces convergent velocity and pressure solutions is addressed in the light of its failure to satisfy the discrete LBB condition. The effect of the element's ill‐disposed (‘spurious’) pressure modes is discussed, and a pressure smoothing scheme is given which gives good results in Newtonian and non‐Newtonian flows at various Reynolds and Deborah numbers. As an example of the element's success in modelling such flows, the problem of pressure differences in flows over transverse slots is studied numerically. The results are compared with experimental observations of such flows. The effect of fluid memory on the relation between first normal‐stress differences and pressure differences is investigated.
A residual method of finite differencing for the elliptic transport problem and its application to cavity flow
Authors: Bhattacharyya T. K. , Datta A. B. 
Published: August 2005

AbstractA residual method of finite differencing the governing differential equation for the elliptic transport problem is presented. The new finite differencing technique is applied to (1) the one‐dimensional transport problem and (2) the cavity flow problem for numerical illustrations. The results indicate the validity of the residual method of finite differencing. The usual method of term‐by‐term finite differencing, and considerations such as central differencing, hybrid differencing and upwind differencing are not needed in the present residual method.
Turbulent flow in a duct with cusped corners
Authors: Rapley C. W. 
Published: August 2005

AbstractAn orthogonal‐cuvilinear‐mesh‐based finite volume calculation method has been applied to the problem of fully developed turbulent flow in the tri‐cusped cornered duct formed when parallel circular rods touch in triangular array. Algebraic stress relations combined with the k‐ϵ turbulence model are used for calculation of the required stresses. A single circulation of turbulence‐driven cross‐plane secondary flow from the core into the duct corner has been predicted in a one‐sixth symmetry region of the duct and the convective transport effects of this flow are seen to have much influence on local mean flow distributions. The turbulence field predicted by the k‐ϵ model showed significant damping in the cusped corner region where turbulent viscosities approached the laminar value. Satisfactory agreement was obtained with the limited local and overall mean flow measurements available.
A critical evaluation of seven discretization schemes for convection–diffusion equations
Authors: Patel M. K. , Markatos N. C. , Cross M. 
Published: August 2005

AbstractA comparative study of seven discretization schemes for the equations describing convection‐diffusion transport phenomena is presented. The (differencing) schemes considered are the conventional central‐ and upwind‐difference schemes, together with the Leonard,1 Leonard upwind1 and Leonard super upwind difference1 schemes. Also tested are the so called locally exact difference scheme2 and the quadratic‐upstream difference scheme.3,4 In multidimensional problems errors arise from ‘false‐diffusion’ and function approximations. It is asserted that false diffusion is essentially a multidimensional source of error. No mesh constraints are associated with errors in function approximation and discretization. Hence errors associated with discretization only may be investigated via one‐dimensional problems. Thus, although the above schemes have been tested for one‐ and two‐dimensional flows with sources, only the former are presented here. For 1D flows, the Leonard super upwind difference scheme and the locally exact scheme are shown to be far superior in accuracy to the others at all Peclet numbers and for most source distributions, for the test cases considered. Furthermore, the latter is shown to be considerably cheaper in computational terms than the former. The stability of the schemes and their CPU time requirements are also discussed.
Laminar flow in a complex geometry: A comparison
Authors: Napolitano M. , Orlandi P. 
Published: August 2005

AbstractThis paper reports on the outcome of a workshop of the IAHR Working Group on Refined Modelling of Flows on the subject of computing laminar flows in complex geometries. Flow inside a channel with a smooth expansion was chosen by the organizers of the workshop as a suitable test case for assessing the capabilities of current numerical methods. The results obtained by fifteen participant groups are presented and compared against a suitable benchmark solution. The most important considerations that emerged at the workshop are briefly reported and the conclusions arising from an analysis and comparison of the various solutions are finally provided.
Dynamic and convective results for a developing laminar unsteady flow
Authors: Creff R. , Andre P. , Batina J. 
Published: August 2005

AbstractDynamic and thermal results for developing laminar pulsed flows in a duct are presented. They have been investigated by means of a finite difference model. This flow is described in terms of an unsteady pulsed flow superimposed on a steady incompressible one with the following main assumptions: a sinusoidal modulation for the pulsation and a uniform wall temperature. Results emphasize the importance of this entry region, where four simultaneous developments occur: steady—dynamic and thermal—and unsteady—dynamic and thermal.
A random vortex simulation of wind‐flow over a building
Authors: Summers D. M. , Hanson T. , Wilson C. B. 
Published: August 2005

AbstractThe random vortex method of Chorin1 provides a numerical simulation of high‐Reynolds number flow in two dimensions. The method can be used to model the viscous interaction of wind with a surface‐mounted obstacle of arbitrary cross‐section. In this paper the method has been used to investigate the flow of wind over common building shapes; an inlet profile is chosen to represent the stationary aspects of the atmospheric boundary layer. The evolution of flow over a short time‐interval after flow initialization is depicted, and a mean value of pressure coefficient, Cp, is calculated over the building perimeter. Some comparison is made with published wind‐tunnel measurements for the case of a surface‐mounted square‐section block and for a building model with 10° roof pitch.