ISSN:0022-1686    

DOI:10.1080/00221689309498855

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The classical depth averaged St. Venant equations for shallow free surface flow are extended to treat problems with nonhydroslatic pressure and nonuniform velocity distributions. The equations required to solve for the additional degrees of freedom are derived by a moment weighted residual method from the fundamental Reynolds equations. The new equations are derived in detail in one horizontal dimension and evaluated for the basic problems of uniform flow and small amplitude waves. With further study and application, these new equations may offer a means for obtaining greater detail over a wider range of problems than is presently practical.

ISSN:0022-1686    

DOI:10.1080/00221689309498856

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In this paper, various modern characteristics-based high resolution nonoscillatory shock-capturing finite difference and Petrov-Galerkin finite element methods are presented for the computation of one-dimensional unsteady free surface flows resulting from a dam-breaking. The adopted schemes come directly from gas flow computations in gas dynamics. The computed results are compared with analytic solutions to assess their validity. It is demonstrated that accurate predictions of high speed open channel flows are obtainable using the present schemes. An analytic solution for sudden formation of a bore wave is also included.

ISSN:0022-1686    

DOI:10.1080/00221689309498857

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A theoretical analysis of high Reynolds swirling flows which allows anticipating - qualitatively - the axial symmetry loss that these flows show under certain conditions, is presented. The basis of such analysis are similar to those applied by hydraulics engineers in free surface flow transition problems. In this paper, theoretical predictions were compared with experimental data, with the result that these predictions are consistent with those data.

ISSN:0022-1686    

DOI:10.1080/00221689309498858

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The unsteady behaviour of gravity cuirents which arises at relatively high discharges, is analyzed using a two-layer model. A self-similar solution that satisfies boundary conditions and a condition at the front of the gravity current is obtained. At high discharges the gravity current is found to take on the shape of an intruding wedge. The solutions considered substantially extend the theoretical range of discharges that produce a twolayer gravity current. Satisfactory agreement with experimental results reported in the literature is obtained.

ISSN:0022-1686    

DOI:10.1080/00221689309498859

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Hydraulic jumps in an abruptly expanding, rectangular and horizontal channel are considered. Particular attention is focused on so-called T-jumps, of which the toe is located upstream from the expansion section. A literature review reveals that T-jumps have not been systematically analysed until now, although considerable effort was made in understanding the phenomenon.

ISSN:0022-1686    

DOI:10.1080/00221689309498860

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

This paper is concerned with the study of the unsteady problem associated with numerical simulation of bore propagation through junctions, and the statement of some of its main features from the point of view of a one dimensional approach. In order to ensure the correct treatment of the involved internal boundary problem when trying to include it in a modelling system, compatibility conditions must be applied with care. The usual technique is to assume the equality among the water levels at the junction. It is shown that this is a valid approximation only for a few simplified cases. A theoretical approach is used to state the unsteady compatibility conditions to be used in the development of a one-dimensional simulation model including supercritical flows and shock propagation through the junction. Some numerical results are presented to illustrate the performance of the suggested techniques. The study does not pretend to be a programming guide but a basic discussion and, as a contribution to the evidence for and against the current technics, it becomes useful to improve modelling systems involving tributaries.

ISSN:0022-1686    

DOI:10.1080/00221689309498861

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In this paper, the systematic longitudinal turbulent intensity measurements of flow in a gravel open-channel have been conducted with a highly accurate one-dimensional LDA-system. The channel bed was roughened with gravels of uniform and non-uniform diameters respectively, and a wide range of H /Ks were considered. In comparison with the smooth bed results, it was found that the bed roughness makes the flow turbulence become well-distributed in the region near the bed and in the case of small H jK% values. With regard to the flow over a non-uniform gravel bed, only the flow region below the maximum gravels is affected by the rough bed, and outside this region, the turbulent intensity distributions could collapse on to a single curve.

ISSN:0022-1686    

DOI:10.1080/00221689309498862

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A study on the friction in unsteady open-channel flow over gravel beds is presented in this paper. Different hydrographs (Table 1) were experimentally investigated. The friction velocity was determined using the equation of mot ion (equation 1). The unsteadiness of the flow was expressed with thedimensionlessClauser parameter (equation 17). It is shown that for a given hydrograph the friction velocity,u*SVis usually larger in the rising branch (accelerating flow) than in the falling branch (decelerating flow), as can be seen in Fig. 3; it reaches its maximum value before the arrival of the peak (D=Dmax) of the hydrograph. During the passage of a hydrograph, the friction coefficient,fis usually larger in the rising branch and smaller in the falling branch; the descending tendency of thef-value in the rising branch is usually followed by a less pronounced ascending one in the falling branch (Fig. 7). The findings on the friction coefficient,f, could be used to understand the field data reported in the literature (Fig. 8).

ISSN:0022-1686    

DOI:10.1080/00221689309498863

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Most tsunamis have previously been believed to be generated by relatively large-scale vertical movements of the sea bed beneath an incompressible sea. This paper considers the possibility that fluid compressibility might be responsible for amplifying seismic waves sufficiently to generate tsunami waves in the open sea. Calculations carried out for a numerical example confirm this as a possibility.

ISSN:0022-1686    

DOI:10.1080/00221689309498864

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor