摘要:

AbstractThe finite element method is applied to incompressible and statistically steady confined turbulent swirling flows. A velocity–pressure formulation is employed. The momentum and continuity equations are solved using a segregated algorithm. Two turbulence models, namely the standard κ–ε model and the algebraic stress model, are considered. It is shown that the algebraic stress model leads to significantly more accurate results in swirling flows compared to the κ–ε model. A novel way of implementing the algebraic stress model is presented in which the stresses are coupled to the Navier–Stokes equations in such a way that they ‘correct’ the effective viscosity hypothesis. This formulation seems to provide a convenient approach for finite elements. In deriving the discretization equations, a streamline‐upwind/Petrov–Galerkin method is employed. Comparisons performed between various upwind schemes show that the numerical solution may be substantially affected by the particular upwind procedure used. The analysis is extended to the prediction of particle motion in turbulent swirling flow fields. Here the fluid turbulence is modelled adopting a stochastic approach. The influence of turbulence modelling on particle movem

ISSN:0271-2091    

DOI:10.1002/fld.1650110602

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractWe discuss in this paper the numerical simulation of compressible viscous flows by a combination of finite element methods for the space approximation, an implicit second‐order multistep scheme for the time discretization and GMRES iterative methods for solving the non‐linear problems encountered at each time step. Numerical results corresponding to flows around aerofoils and aerospace vehicles illustrate the possibilities of these meth

ISSN:0271-2091    

DOI:10.1002/fld.1650110603

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractWe describe an upwind finite element method aimed at numerically simulating the two‐dimensional transonic flow of a reactive gaseous mixture. The method uses in particular a triangular finite element mesh, with an adaptive procedure based on mesh refinement by triangle division, and an upwind non‐oscillatory scheme based on an approximate Riemann solver for the evaluation of the convective terms for all species. Results concerning the reactive interaction of two supersonic gaseous jets are presen

ISSN:0271-2091    

DOI:10.1002/fld.1650110604

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractHeterogeneous equation systems in a pair of coupled co‐ordinate systems are solved by a finite element method. The specific physical application studied is the effect of temperature on single‐well chemical tracer (SWCT) tests to measure residual oil saturation (volume fraction of immobile oil phase) remaining after waterflooding of an oil reservoir. Since temperature effects are caused by injecting cooler surface fluid down a well into a warm reservoir, the vertical temperature profile in the wellbore as well as the temperature distribution in the porous oil‐bearing layer must be considered.The entire system is modelled to account for the different transport mechanisms. However, it is expedient to divide the connected geometrical region into two model domains. The equations for each submodel are expressed in an appropriate set of co‐ordinates. The variational formulation of each model is then discussed.A significant temperature effect on the estimation of residual oil saturation occurs when the radial temperature and concentration wave propagation speeds in the porous formation are about the same. In this case the temperature gradient is located across the chemical tracer bank, causing the chemical reaction rate to vary radially. The temperature effects are demonstrated for two actual field tests in complex res

ISSN:0271-2091    

DOI:10.1002/fld.1650110605

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractAxisymmetric, ideal MHD configurations with steady flow are computed by the finite‐element method. Rectangular elements with four to nine nodes are used. The equilibria are obtained in flux co‐ordinates by mesh rearrangement. The properties of the linearized motions around an equilibrium state are studied by a normal‐mode analysis. Dissipation is taken into account. Applying the Galerkin method leads to a large‐scale complex eigenvalue problem

ISSN:0271-2091    

DOI:10.1002/fld.1650110606

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA method for the uncoupled solution of three‐dimensional biharmonic problems for the vector potential in viscous incompressible flow is presented. The strategy applied in a previous work on vector Poisson equations is employed to reduce the vector fourth‐order problem to a sequence of scalar biharmonic problems. A finite element aimed at the implementation of the method in a discrete version is considered. A conjugate gradient algorithm which is particularly efficient for the uncoupled solution method is also descri

ISSN:0271-2091    

DOI:10.1002/fld.1650110607

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThis paper describes a new approach to discretizing first‐ and second‐order partial differential equations. It combines the advantages of finite elements and finite differences in having both unstructured (triangular/tetrahedral) meshes and low‐order physically intuitive schemes. In this ‘co‐volume’ framework, the discretized gradient, divergence, curl, (scalar) Laplacian, and vector Laplacian operators satisfy relationships found in standard vector field theory, such as a Helmholtz decomposition. This article focuses on the vorticity–velocity formulation for planar incompressible flows. The algorithm is described and some supporting numerical evidenc

ISSN:0271-2091    

DOI:10.1002/fld.1650110608

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe immiscible displacement problem in reservoir engineering can be formulated as a system of partial differential equations which includes an elliptic pressure–velocity equation and a degenerate parabolic saturation equation. We apply a sequential numerical scheme to this problem where time splitting is used to solve the saturation equation. In this procedure one approximates advection by a higher‐order Godunov method and diffusion by a mixed finite element method. Numerical results for this scheme applied to gas–oil centrifuge experiments are

ISSN:0271-2091    

DOI:10.1002/fld.1650110609

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA computational study of viscous flow between two eccentrically rotating cylinders is presented in which the effect of viscous dissipation is taken into account. The space discretization is based on piecewise linear finite elements with velocity stabilization, while the method of characteristics is used for time integration. Numerical results illustrate the efficiency of the adopted approach.

ISSN:0271-2091    

DOI:10.1002/fld.1650110610

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractIterative versions of the adaptive implicit–explicit method are presented for the finite element computation of flow problems with particular reference to incompressible flows and advection–diffusion problems. The iterative techniques employed are the grouped element‐by‐element and generalized minimum residual

ISSN:0271-2091    

DOI:10.1002/fld.1650110611

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY