摘要:

AbstractA semi‐implicit finite difference method for the numerical solution of three‐dimensional shallow water flows is presented and discussed. The governing equations are the primitive three‐dimensional turbulent mean flow equations where the pressure distribution in the vertical has been assumed to be hydrostatic. In the method of solution a minimal degree of implicitness has been adopted in such a fashion that the resulting algorithm is stable and gives a maximal computational efficiency at a minimal computational cost. At each time step the numerical method requires the solution of one large linear system which can be formally decomposed into a set of small three‐diagonal systems coupled with one five‐diagonal system. All these linear systems are symmetric and positive definite. Thus the existence and uniquencess of the numerical solution are assured. When only one vertical layer is specified, this method reduces as a special case to a semi‐implicit scheme for solving the corresponding two‐dimensional shallow water equations. The resulting two‐ and three‐dimensional algorithm has been shown to be fast, accurate and mass‐conservative and can also be applied to simulate flooding and drying of tidal mud‐flats in conjunction with three‐dimensional flows. Furthermore, the resulting algorithm is fully vectorizable for an efficient implementation on

ISSN:0271-2091    

DOI:10.1002/fld.1650150602

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractIt is known that Jameson's scheme is a pseudo‐second‐order‐accurate scheme for solving discrete conservation laws. The scheme contains a non‐linear artificial dissipative flux which is designed to capture shocks. In this paper, it is shown that the, shock‐capturing of Jameson's scheme for the Euler equations can be improved by replacing the Lax‐Friedrichs' type of dissipative flux with Roe's dissipative flux. This replacement is at a moderate expense of the calcu

ISSN:0271-2091    

DOI:10.1002/fld.1650150603

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe lag‐entrainment method, which is a well‐established integral method for predicting the development of turbulent boundary layers, is used in this study to predict two‐dimensional turbulent separated flow. The method is used in an inverse mode, in which the displacement thickness is specified together with other integral parameters of the boundary layer. It is concluded that the prediction of two‐dimensional separated flow by an integral method is feasible, but there is a need for accurate data for both equilibrium and general separated flows for making a com

ISSN:0271-2091    

DOI:10.1002/fld.1650150604

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA new computational methodology with emphasis on using an overlapping grid technique and a multigrid method has been developed. The main feature of the present overlapping‐grid system is of extended flexibility to deal with three‐dimensional complex multicomponent geometries. The multigrid method is incorporated into this technique to accelerate the convergence of the numerical solution. The current scheme has been applied for computations of the laminar flows in the multicomponent configuration of internal combusion engines. The flow is governed by three‐dimensional, time‐dependent, incompressible Navier‐Stokes equations with the continuity equation. Atime‐independentgrid system is constructed for the moving boundary, i.e. the moving piston in the engine. This grid system is entirely different from others for the same problem in previous works. The performance of the present method has been validated by comparing the results with those from an equivalent, single‐grid method and those from experiments. In addition, the flexibility and potential of the method has been demonstrated by calculating several cases which would be very difficult to be handled by

ISSN:0271-2091    

DOI:10.1002/fld.1650150605

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe paper presents a modification to two well‐known non‐iterative implicit finite‐difference schemes for confined and unconfined boundary‐layer‐type flows. The modification aims at improving the accuracy of these schemes by reducing the adverse effect of linearization, which is inherent in both of them. Using the present improved scheme, the same level of accuracy of the results could be obtained with large mesh sizes in the flow direction (coarse grid). The modification is done by adding a local iterative procedure at each computational step in the flow (marching) direction. As an example, to demonstrate the proposed modification, the simple case of developing forced convection in the entry region of concentric annuli has been considered. The results are presented, which prove the applicability of the proposed modification and show its effect on the obtained accuracy and on the required comp

ISSN:0271-2091    

DOI:10.1002/fld.1650150606

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThe governing equations required to analyse the linear (viscous) stability of low‐speed reacting flows are derived and a solution method based on initial value problems is described. The algorithm accurately reproduces the neutral stability curve for a non‐reacting viscous shear layer, thus providing partial validation. The results for premixed and non‐premixed flames in planar shear layers are presented and disc

ISSN:0271-2091    

DOI:10.1002/fld.1650150607

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650150608

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650150601

出版商:John Wiley&Sons, Ltd    

年代:1992

数据来源: WILEY