摘要:

This study has resulted in the development of criteria for the design of riprapped cantilevered pipe spillway plunge pool energy dissipators having the shape of self-formed scour holes. A literature review revealed information on the general principles of local scour at pipe exits, but inadequate practical information on scour and prevention of scour at pipe outlets. Presented herein are a research plan to provide the needed information, a description of the experimental apparatus and instrumentation, and an explanation of the experimental methods. Additional background information is a description of the scour process, and the geometry of the jet after emerging from the pipe.

ISSN:0022-1686    

DOI:10.1080/00221688809499198

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Critical flows may occur at more than one depth in channels having compound cross-sections (cross-sections with flood plains). The possibility of multiple critical depths affects the water-surface-profile calculations. Presently available algorithms determine only one of the critical depths which may lead to large errors. In this paper, computational procedures are presented for computing all the possible critical depths in general symmetrical, compound channels. They incorporate a general definition of Froude number based on the one-dimensional unsteady momentum and continuity equations. In these procedures, the total number of critical depths possible in a cross-section for a given discharge are first determined and then their values are computed one by one in an efficient manner. A procedure is presented to design a compound channel section so that there is only one critical depth, thereby reducing the range of flow depth over which flow may be highly unstable. Two typical examples are presented to illustrate the effect of multiple critical depths on the water-surface profile computations.

ISSN:0022-1686    

DOI:10.1080/00221688809499199

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

This experimentally based study was aimed at determining the equilibrium thicknesses and forms of icerubble accumulations beneath barges moving through ice-covered channels. In addition to significantly increasing the resistance encountered by barges, severe accumulations of ice rubble may cause them to ground and become stuck on channel beds or on exit sills of locks. It is shown that significant amounts of ice may accumulate beneath a barge moving at creeping speed through a navigation channel covered by a sheet of ice, and that accumulation thickness decreases with increasing barge speed. A barge moving slowly through a cover of broken ice, however, may develop a false-bow which deflects ice rubble around the barge such that little ice accumulates beneath it. Increasing barge speed caused more ice to be swept beneath the barge as the false-bow diminishes in size, and eventually a wave-form accumulation develops beneath it. With further increases in speed, accumulation thickness diminishes. An analogy is drawn between icerubble accumulations and sedimentary bedforms in water or air flows.

ISSN:0022-1686    

DOI:10.1080/00221688809499200

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

In finite difference solutions of the kinematic equations for overland flow, uncontrolled numerical diffusion can be introduced into a system by the finite difference scheme. A formulation for overland flow based on the Muskingum-Cunge routing procedure [4] incorporating a four-point numerical scheme is described and the results of numerical experiments are presented, comparing the method with other kinematic routing methods. The experiments verify the dependence of kinematic routing accuracy on grid spacing and on the position of the space derivative, and show that the Muskingum-Cunge results are independent of grid spacing. By comparing the conventional kinematic routing formulation with the Muskingum-Cunge formulation, it is shown that a centred scheme is the most appropriate for overland flow routing if a fixed grid formulation of the kinematic equations is employed.

ISSN:0022-1686    

DOI:10.1080/00221688809499201

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The development of a two-dimensional mathematical model to calculate flow characteristics in channels of compound cross-section is described. The model utilizes a previously developed depth-averaged form of thek-ε turbulence model. The model is tested against velocity and bed shear stress data taken from the literature and obtained in laboratory flumes modelling a main channel/flood plain geometry. Comparisons between these data and model predictions show generally good agreement. One necessary input to the model is the dimensionless transverse eddy diffusivity,e*ast;, which has a significant influence on the predicted distributions. A value of0.15, adopted from the literature for rectangular laboratory flumes, is shown to be appropriate for laboratory compound channels. However, application of the model to natural compound channels requires further investigation of this parameter.

ISSN:0022-1686    

DOI:10.1080/00221688809499202

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Two undistorted physical models at scales of 1 : 100 and 1 :50 were built to investigate the hydraulic and thermal properties of the Shuaiba nearshore area in Kuwait. The models reproduced the southern breakwaters of the Shuaiba harbor and the three cooling water intakes and five heated effluent and process water outlets. The 1 : 100 model was operated at frozen tidal levels under steady-state conditions. In the 1 :50 model, transient conditions were simulated, allowing the tidal levels and currents to vary over one complete tidal cycle. The models were constructed in the 56 x 37 m basin of the Hydraulic Laboratory at the Kuwait Institute for Scientific Research (KISR).

ISSN:0022-1686    

DOI:10.1080/00221688809499203

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Resistance to flow due to an obstruction in the form of bridge piers give rise to many problems which are of engineering interests. An experimental study of the effects caused to some of these problems due the introduction of a vertical longitudinal slot to an obstruction in the form of a pier is carried out. Experiments are performed in the subcritical range of Froude number to measure the drag force and the energy loss with various slot width to pier thickness ratios, and the results are compared with those of conventional solid piers. The results obtained show a substantial reduction in the drag coefficient for slotted piers compared to the solid ones under the same flow conditions. Experiments also indicate the existence of an optimum value of slot width to pier thickness ratio. The loss in the total energy of the flow is also found to be smaller for the slotted pier compared to a similar solid pier.

ISSN:0022-1686    

DOI:10.1080/00221688809499204

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Experiments have been carried out to investigate the hydrodynamic interaction between a train of regular incident waves and a partially immersed, substantially rectangular obstacle in an essentially two-dimensional domain. The interaction is considered for both fixed and floating obstacle modes. Experimental measurements have been taken of the obstacle reflection and transmission characteristics in both modes, together with the obstacle motion response in the floating mode, and comparison is made with the predictions of linear diffraction theory. The results of the investigation have enabled identification of the conditions under which the use of potential theory alone becomes invalid due to the significant presence of energy dissipation mechanisms in the interactive process.

ISSN:0022-1686    

DOI:10.1080/00221688809499205

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A theoretical study of small amplitude waves generated by a sinusoidally oscillating wedge-shape plunger in a finite depth wave tank is presented in this paper by using a semi-analytical method, the boundary collocation method. The ratios between wave amplitude and wavemaker stroke are established. This theory is compared to the conformal transformation method and laboratory measurements. Results show that this theory is in reasonably good agreement with the laboratory data.

ISSN:0022-1686    

DOI:10.1080/00221688809499206

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221688809499207

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor