摘要:

In ihis report, a joint IAHR and UNESCO panel addresses the current developments in hydraulic engineering and their implications for the education of hydraulic engineers. The framework of underlying basic sciences, geosciences and engineering sciences and the large variety of engineering subjects involved must be seen in the broader context of the natural and social environment. In addition to its classical tasks, hydraulic engineering has evolved to deal with water quality, environmental issues and ecology, and it is further broadened by the new challenges posed by the need for sustainable development and by the threat of global changes. New developments in science and technology and computer sciences must be reflected both in contents and methods of teaching. Education must also provide engineering skills and procedures as well as professional preparation including the ability to work in interdisciplinary teams. In view of these developments, continuing education will have a major role to play, and large-scale systems and international aspects will be of increasing importance. These developments’ call for suitable IAHR activities.

ISSN:0022-1686    

DOI:10.1080/00221686.1994.10750032

出版商:Taylor & Francis    

年代:1994

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221686.1994.10750033

出版商:Taylor & Francis    

年代:1994

数据来源: Taylor

摘要:

This paper summarises developments in column separation experimentation in pipes at the University of Adelaide, South Australia. An experimental apparatus with a 37.2 m copper pipe of 22 mm diameter has been constructed. A very fast closure ball valve has been developed which provides a closure time of 5 to 10 milliseconds. Two problems in the development of the experimental apparatus are discussed in detail. First, a problem was encountered with the placement of two 150 mm long How visualisation polycarbonate sections in the pipeline. The discrete vapour cavity numerical model is used to simulate the effect of the presence of the polycarbonate sections in the experimental apparatus. Second, problems in obtaining accurate pressure readings from strain-gage type pressure transducers have also occurred. Analysis of the experimental results has led to the development of solutions to overcome these problems when investigating column separation in pipelines.

ISSN:0022-1686    

DOI:10.1080/00221686.1994.10750034

出版商:Taylor & Francis    

年代:1994

数据来源: Taylor

摘要:

In this study a maximised cross-correlation technique is applied to two very different experiments. The first is a laminar, slowly developing experiment where the main scales of the motion are comparable to the image size. Here extensive use of multiple passes with the technique and various filters are applied to replace erroneous measurements. The second experiment has both laminar and turbulent regions of flow, and in addition, many of the scales of motion are smaller than the correlation window size. Mean velocities are resolved in this application, as well as a qualitative impression of the turbulent fluctuations.

ISSN:0022-1686    

DOI:10.1080/00221686.1994.10750035

出版商:Taylor & Francis    

年代:1994

数据来源: Taylor

摘要:

For the last decades, stepped spillways have become a popular method for handling flood releases. The flow regime over a stepped chute can be either a nappe flow or skimming flow regime. The energy dissipation of both flow regimes are analysed. The results are compared with experimental data. For long chutes where uniform flow conditions are reached, higher energy dissipation takes place in a skimming flow regime. But, for short channels, nappe flows would dissipate more kinetic energy than skimming flows.

ISSN:0022-1686    

DOI:10.1080/00221686.1994.10750036

出版商:Taylor & Francis    

年代:1994

数据来源: Taylor

摘要:

End depth in trapezoidal and exponential channels is analytically determined using the momentum approach and the Boussinesq approximation. Simple procedures are presented to estimate the discharge using the end depth measurement. The momentum equation incorporating the effect of streamline curvature is also used to obtain the non-dimensional water surface profiles in front of a free overfall.

ISSN:0022-1686    

DOI:10.1080/00221686.1994.10750037

出版商:Taylor & Francis    

年代:1994

数据来源: Taylor

摘要:

This paper examines the mixing processes that develop when a buoyant jet from a round outfall pipe enters a shallow moving body of water in a direction perpendicular to the current and focuses on the role played by the bed shear velocity developed in the receiving water. Different velocity profiles in the receiving water were produced using a triggering fence to modify the profile and hence the bed shear velocity. These changes simulated variations in the roughness of the bed. The results of an experimental study are presented where the effects related to the magnitude of the current, the bed shear velocity, and the locations of the free and bed boundaries on the jet mixing parameters are quantified. Findings are outlined which show that the dilutions of buoyant jets are significantly influenced by these parameters. Other mixing features are discussed including a “total cross sectional dilution” parameter and a novel width parameter. The role played by the Coanda Effect in influencing the mixing of the jet is addressed and mixing parameter results are compared with deep (unconlined) and shallow (confined) stationary results.

ISSN:0022-1686    

DOI:10.1080/00221686.1994.10750038

出版商:Taylor & Francis    

年代:1994

数据来源: Taylor

摘要:

Steady-state waves impinging obliquely on a coast are used to model a tsunami wave train as it moves from the open sea onto a continental shelf. The shelf edge is modelled with a discontinuity in depth, and on the landward side of the shelf edge the mean depth decreases linearly with distance to a value of zero at the coast line. Reflected waves in the open sea are found to have a reflection coefficient of unity as a result of a requirement that the solution be bounded at the shore line. The angle of wave incidence is found to have a significant effect upon wave amplifications near resonance frequencies but to have very little effect upon the magnitude of these resonance frequencies. Wave periods and wave length components parallel to the shore line are not changed as waves pass over the shelf, but wave length components normal to the shore line change significantly in this region.

ISSN:0022-1686    

DOI:10.1080/00221686.1994.10750039

出版商:Taylor & Francis    

年代:1994

数据来源: Taylor

摘要:

Measurements of velocity arid temperature distributions were made in entrances of tidal harbours at reduced scale. The influences of the geometry of the entrance and tidal water level changes on the how in the harbour entrance and the exchange of water between harbour and river were studied. Density differences were absent. The formation and decay of gyres in the harbour is shown to correspond with variations in advective and tur bulent transports of heat through the harbour entrance.

ISSN:0022-1686    

DOI:10.1080/00221686.1994.10750040

出版商:Taylor & Francis    

年代:1994

数据来源: Taylor

摘要:

Mixing in a two-layer stably stratified fluid by a turbulent buoyant jet was studied primarily through a laboratory experiment. A non-swirling jet was discharged vertically downwards in a fluid system consisting initially of a top layer of fresh water and a bottom layer of salt water. In total, six experimental cases were performed where the jet exit velocity and the density difference between the top and bottom layer were varied. The total depth and the initial depth of the two layers were approximately constant in all the cases studied, and the jet exit was located in the middle of the initial freshwater layer. Both vertical density profiles and time series of density in selected points were determined from conductivity measurements using a data sampling system involving up to 16 probes. The mixing efficiency, defined as the percentage of the supplied kinetic jet energy that is used for increasing the potential energy of the fluid system, was related to a densimetric Froude number based on the intermediate layer depth. Overall, the calculated jet mixing efficiencies displayed higher values than corresponding efficiencies for destratification with air-bubble plumes.

ISSN:0022-1686    

DOI:10.1080/00221686.1994.10750041

出版商:Taylor & Francis    

年代:1994

数据来源: Taylor