摘要:

AbstractTwo numerical methods for solving the problem of solute transport in unsteady flow in unconfined aquifers are studied. They are the method of characteristics (MOC) based on the finite difference method (FDM), and the finite element method (FEM). The FEM is further subdivided into four schemes: moving mesh, pseudo‐Lagrangian (FEM1); stationary mesh, pseudo‐Lagrangian (FEM2); pseudo saturated‐unsaturated, Eulerian (FEM3); and non‐stationary element, Eulerian (FEM4).Experiments on a one‐dimensional flow case are performed to illustrate the schemes and to determine the effect of discretization on accuracy. In two‐dimensional flow the above methods are compared with experimental results from a sand box model. Results indicate that for a similar degree of accuracy, the FEM requires less computational effort than the MOC. Among the four FEM schemes, FEM4 appears to be most attractive as it is the most efficient and most convenie

ISSN:0271-2091    

DOI:10.1002/fld.1650030203

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractFinite difference methods for solving the linear model describing unsteady state flow in pipelines are considered in the present paper. These methods are compared with each other in order to determine the best one, which meets the criteria of accuracy and relatively small computation time.

ISSN:0271-2091    

DOI:10.1002/fld.1650030204

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractThis paper presents the finite element method for the analysis of unsteady viscous flow of fluid at high Reynolds numbers. The method is based on the explicit numerical integration scheme in time and uses three node triangular finite elements. For the convenience of the formulation, slight compressibility is considered. For the explicit scheme, the selective lumping two step scheme has been successfully employed. Vortex shedding behind a cylinder has been computed and compared with the conventional experimental results. The results agree favourably when both schemes are compared.

ISSN:0271-2091    

DOI:10.1002/fld.1650030205

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650030206

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractA finite element model to tackle the moving boundary problem of wave run‐up on moderately steep slopes is developed. The special aspects considered in this study are (1) the modification of shallow water equations to accommodate the effect of vertical accelerations and (2) the use of Lagrangian acceleration coupled with an element that adapts itself to the moving boundary closely. The pressure term in the one‐dimensional momentum equation is derived using the Eulerian equation in the vertical direction. This takes care of the vertical accelerations which are significant during the motion of a wave on moderately steep slopes. The element near the boundary is allowed to change its dimension so that the fluid boundary is closely followed. Such a flexible element precludes the need for approximation of the variables with regard to the indefinite position of the boundary. This element is split into two when its dimension becomes unduly large compared to the unchanging elements. The need for such a splitting is shown by an examination of the entries in the global matrix. Results of water profile as a wave runs up a structure are given. A brief history of the work on similar problems is outli

ISSN:0271-2091    

DOI:10.1002/fld.1650030207

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

摘要:

AbstractPrevious papers12have drawn attention to the sustained oscillations (‘noise’) in the solution by successive over‐relaxation of the equations from the finite difference approximation of regional groundwater flow including ephemeral streams. This paper shows that the trouble can be avoided by introducing an averaging step in the algorithm; the trouble can also be avoided by ‘under‐relaxation’ but this is far less efficient tha

ISSN:0271-2091    

DOI:10.1002/fld.1650030208

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650030209

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY

ISSN:0271-2091    

DOI:10.1002/fld.1650030202

出版商:John Wiley&Sons, Ltd    

年代:1983

数据来源: WILEY