摘要:

Temporal lag effects, which are viewed as the inability of an alluvial system to immediately respond to changing flow conditions, are investigated under bed load sediment transport conditions. Temporal lag effects are investigated experimentally and a temporal lag model is formulated. The temporal response ofthe alluvial system is characterised by a single variable, the equivalent steady flow rate. An impulse model is used to develop a general temporal solution. The performance of the temporal lag model is tested against measured data and is verified. A numerical model which incorporates the temporal lag model and its performance are also briefly described.

ISSN:0022-1686    

DOI:10.1080/00221689009499144

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A general model is presented for predicting entrainment conditions for nonuniform, noncohesive sediments. The model is based on an analysis of the moments of forces acting on a particle at the condition of incipient motion. Particle geometry and packing arrangement are accounted for as well as variations of near bed flow velocity and drag and lift coefficients for a wide range of flow conditions. Model predictions agree well with laboratory and field measurements for uniform sediments and for protrusion and relative size effects.

ISSN:0022-1686    

DOI:10.1080/00221689009499145

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

From three disparate examples studied in the field and the laboratory, it is found that the erosion of consolidated cohesive soils is very much a function of the transport properties of even sparse amounts of granular material overlying the cohesive soil or carried by the eroding stream. Since erosion of consolidated cohesive sediments by clear water is a complex function of the characteristics of the cohesive sediment and not readily understood, while sediment transport of granular material, is relatively much better known, this concept greatly simplifies understanding of erosion of a cohesive bed.

ISSN:0022-1686    

DOI:10.1080/00221689009499146

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The influence ofa small slope and weak sedimentation on the behavior of non-conservative turbidity current heads are experimentally investigated. Experiments are carried out in the slope range 0°≤Θ≤2.1° with two different sediments to get a reasonably wide range of the ratio of fall velocity of particles,vs, to the velocity of the head,Uf. The limiting case ofvs= 0 (conservative gravity current) is investigated by a series of saline gravity current experiments.

ISSN:0022-1686    

DOI:10.1080/00221689009499147

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Experiments have been carried out in the laboratory concerning the efficiency of settling basins. The data indicate that the existing methods of their design are not satisfactory. Analysis of all the available data has led to a new relationship for the efficiency. The parametersL/Dandw/u, are found to govern the efficiency.

ISSN:0022-1686    

DOI:10.1080/00221689009499148

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Using the method described in Part 1. the effect of surface roughness of flow passages, runner seal clearance and the Reynolds number on the hydraulic performance and loss distribution coefficientVis quantitatively made clear.Voptwhich is the value ofVat the optimum efficiency point varies within the range of approx. 0.96-1.05 times the original value when the surface roughness of all of flow passages in a model turbine becomes 0.5-2 times the original roughness, however, does not vary with the runner seal clearance. When the Reynolds number varies with the change of head or water temperature, the admissible surface roughness of each How passage decreases as the Reynolds number increases, thus each friction coefficient becomes the value corresponding to the rough surface region. As a result, the change of performance andVoptdue to the change of the Reynolds number becomes smaller in comparison to that in the case with smooth surfaces. On the contrary, when the head, water temperature and surface roughness are unchanged and the Reynolds number varies only with the size of turbine, the relative roughness decreases as the Reynolds number increases and becomes the value in the smooth surface region. As a result, the change of performance andVoptis larger than the former case mentioned above. In other words, the effect of roughness cannot be neglected for examining the effect of the Reynolds number onVopt.

ISSN:0022-1686    

DOI:10.1080/00221689009499149

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221689009499150

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221689009499151

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221689009499152

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Design Of BreakwatersEdited by the Institution of Civil Engineers, U.K. Published by Thomas Tellbrd Ltd., Thomas Telford House, 1 Heron Quay, London E14 9XF, U.K. 406 pages, 1988, hardcover.

ISSN:0022-1686    

DOI:10.1080/00221689009499153

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor