摘要:

Based on some present and past features of water resources in developed countries, some future trends are outlined towards the development of water sciences.

ISSN:0022-1686    

DOI:10.1080/00221688809499219

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

An entrainment model is developed which includes the effect of the buoyancy flux by molecular diffusion across a density interface. This effect is incorporated into the conservation equation for turbulent kinetic energy through a “diffusion parameter”RiPe-1/2, whereRiis the bulk Richardson number andPethe Peclet number. As RiPRiPe-1/2e increases and approaches a critical limiting value the net entrainment, defined as the rate of deepening of the mixed layer, becomes zero. Based on a numerical study and on results from two experiments of different scales, it is shown that the limiting value of this parameter for entrainment to occur is approximately 10 for a salt-stratified system, though this value may depend on the diffusivity of the stratified component.

ISSN:0022-1686    

DOI:10.1080/00221688809499220

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A programme of experimental study on simple circular single hinged flap gates is reported. Energy losses resulting from the flow constriction created are found to be largely dependent upon the flowrate and the gate's self weight when subjected to a tailwater surcharge. Guidance on gate selection and head loss implications in the literature is sparse and design curves are therefore presented here to partially fill this gap. These show that the total energy loss at the outfall resulting from the use of heavy gates can be more than double the kinetic energy head of the pipe flow, representing the normal pipe “exit” losses.

ISSN:0022-1686    

DOI:10.1080/00221688809499221

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Experiments were carried out in the 18 km long, 600 mm diameter pipeline at the thermal power station complex at Tusimice in Czechoslovakia. This pipeline carries a pumped slurry of pulverised ash and slag to the final disposal lagoon. The soluble polymer, Separan AP-302, was injected into this pipeline as a possible means of increasing the solids transport rate to 2 Mm3per annum. Pressure gradients, velocities, solids concentration and polymer concentration were measured and gave encouraging results. Laboratory tests in small pipes with the same materials showed a high level of drag reduction and no adverse behaviour due to the solids loading.

ISSN:0022-1686    

DOI:10.1080/00221688809499222

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

We think that to progress in the mechanism of regular and breaking wave propagation, it is necessary to realize more physical studies from which only coherent theories can be established. This method is applied in the paper. We explain in this way the physical meaning of the regular wave propagation but also the complex mechanism of their breaking shape even over an horizontal or inclined bottom. We present interesting results concerning breaking wave sollicitations on vertical breakwaters and we compare their free surface shapes with the corresponding profiles obtained in our laboratory. We propose here a fundamental study which is defining important computation possibilities of complex phenomena like the regular and breaking wave action on fixed structures.

ISSN:0022-1686    

DOI:10.1080/00221688809499223

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The earthen dam breach erosion is analyzed using dimensionless analytical solutions, with rectangular and triangular representations for the breach section. Data for the historical failures of South Fork and Teton Dams are used to test these solutions. A comparison with the BEED model shows usefulness of these solutions.

ISSN:0022-1686    

DOI:10.1080/00221688809499224

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Turbulent round buoyant jets discharging into linearly density-stratified stagnant fluids are studied. The sensitivity of the assumed entrainment relations and profile shapes in traditional integral models is explored. A different representation of the density profile is developed in order to more correctly represent the cross-sectional density distribution. In an experimental study, the dilution of a passive tracer along the jet trajectory, the maximum height of rise, and terminal dilution are measured. Measured center-line dilutions and jet widths are in essential agreement with model predictions with any of several previously proposed entrainment relations. It is found that jet mixing is not significantly influenced by either the ambient density gradient or the gravitational spreading layer from the jet collapse. There is some evidence of re-entrainment of jet fluid for horizontal nonbuoyant discharges. The integral model tends to under-predict the maximum height of jet rise and the associated dilution; this is apparently due to the inability to model the dynamics near that position correctly.

ISSN:0022-1686    

DOI:10.1080/00221688809499225

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The equations of motion are developed for an unrestrained revetment block lying on a free-flowing filter layer, subject to harmonic base pressure during wave downrush. The resulting trajectories are calculated numerically and depicted at discrete time intervals. The influence is then estimated of progressive decreases both in the spacing of adjacent blocks and in the filter layer permeability. Some consideration is also given to small-amplitude, continuous oscillations. It is suggested that reductions in filter thickness and permeability are more effective in reducing block uplift than are increases in block thickness.

ISSN:0022-1686    

DOI:10.1080/00221688809499226

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221688809499227

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221688809499228

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor