摘要:

A numerical model to simulate the performance of primary clarifiers, with emphasis on the prediction of the velocity field and concentration distribution, is presented. The model is restricted to those mean steady flows which are isothermal, neutral density, low in solids concentration and nearly two-dimensional. The model employs the Strip Integral Method (SIM) to solve the governing differential equations of continuity, momentum and mass transport. This method is an improvement over the plug flow models in that it can reproduce the main features of the flow such as the boundary layer, recirculation and distribution of the dispersion coefficient. It has an advantage over the finite element and the finite difference models since it requires relatively low computer storage and computational time.

ISSN:0022-1686    

DOI:10.1080/00221688509499358

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The hydraulicjump in a stilling basin with an abrupt rise of the channel bottom is analysed by an elementary hydraulic approach. Results obtained include an expression for the sequent flow depth, the head loss due to the hydraulic jump formation and the length characteristic in terms of the inflow Froude-number and the step height. A detailed investigation is given of the transition between the jump and the jet formation. All results are presented in terms of design quantities, and the computation procedure is illustrated by an example.

ISSN:0022-1686    

DOI:10.1080/00221688509499359

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Aturbulence model is used to study the behaviour of round buoyant jets before the point of neutral buoyancy in stably linear stratified environments. The calculation of the centerline velocity, density, turbulent kinetic energy, half-width of buoyant jets and the profiles of turbulent kinetic energy, turbulent dissipation function, turbulent shear stress and turbulent heat flux are made for a wide range of exit densimetricFroude numbers and ambient temperature stratifications. A unified scaling law is derived for normalization of these results. The correlation of the predicted results shows that the established zone of buoyantjet in the stably linear stratified environment may be divided into three regions: non-buoyant region, intermediate region and plume region. The variation of centerline velocity, density and turbulent kinetic energy and the spread of velocity half-width along the axial line for both uniform and linearly stratified environments for a given exit densimetric Froude number is found to converge to a single curve under the unified scaling law. The profiles of mean velocity, mean temperature and turbulent transport properties are given.

ISSN:0022-1686    

DOI:10.1080/00221688509499360

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

This paper presents the results ofan experimental study on the diffusion of plant turbulent buoyant surface jets and jumps. For the buoyant surface jet, a diagram showing the growth of its thickness in terms of its thickness at the outfall with the dimensionless longitudinal distance for a wide range of source Richardson numbers (Ri0) has been developed. The structure of the mean velocity in the surface jet has also been studied for a fange ofRi0. It has been found that for surface jumps with supercritical densimetric Froude numbers as large as about 9 there is hardly any entrainment on its lower side. The dimensionless surface profile of the surface jump has been found to be the same as that of the more familiar open channel hydraulicjump. The mean velocity field in the surface jump has also been studied. A comprehensive diagram has been developed to predict whether a surface jet, or surface jump or drowned jump will occur for given values ofRi0and the downstream depth of stratified flowin terms of the source thicknessb0.

ISSN:0022-1686    

DOI:10.1080/00221688509499361

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

The long wave energy attached to the grouping of natural waves has been shown to play a very important role in the design of mooring systems, offshore terminals, floating structures, harbours, etc. Therefore, in model testing, efforts should be made to reproduce only the correct amount of long wave energy present in nature. However, when only traditional first-order control signals are applied to the wave generator errors will be introduced. Hence, a second-order signal has to be calculated and imposed in order to obtain satisfactory long wave conditions in the physical model. The necessary signal and transfer functions are outlined below for all common types of wave boards. It is demonstrated that dependent on the type (piston, hinged, etc.) considerable differences can be found in the amplitude of the required second-order control signal. Also the erroneous longwave energy is assessed in case of only first-order wave generation. The results indicate that in such situations significant deviations from the correct long waves may appear, but it turns out that these errors are to a certain extent independent of the actual type of wave board used for the wave generation. The typical range of the deviations is shown to be from − 100% to about + 300% if second-order (compensation) signals are not applied.

ISSN:0022-1686    

DOI:10.1080/00221688509499362

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Pumping abrasive solids such as sand always leads to damage to the pumping unit. As a contribution to the solution of this problem a modified jet pump is introduced here based on the hydrocyclone principle. For this reason the device has been called the “Cyclone Pump”. The drive is achieved by an exterior pump. The output of the cyclone pump with respect to the driving system is rather low (20-30%). Consequently application is only recommended for cases in which energy costs are not significant, for instance when the pump is a small part of a large system. In the Delft Hydraulics Laboratory the cyclone pump has been successfully applied to the continuous pumping of sand-water mixtures for a sand flume and river scale models with movable bed. In this paper the flow pattern in the cyclone pump and its separation power i.e., its ability to separate solids from the flow, are treated qualitatively. In addition, the results of some preliminary experiments are given.

ISSN:0022-1686    

DOI:10.1080/00221688509499363

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Flexible dams are in use as both temporary and permanent structures in a number of countries and consist of a flexible membrane secured to the channel bed.

ISSN:0022-1686    

DOI:10.1080/00221688509499364

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

DEVELOPMENTS IN HYDRAULIC ENGINEERING- 1 edited by P. Novak Elsevier Applied Science Publishers Ltd., 22 Rippleside Commercial Estate, Barking, Essex 1G11 OSA, England. ISBN 0-85334-227-X, 240 pp., 18 Tables and 96 Illustrations. Price £ 30.00.

ISSN:0022-1686    

DOI:10.1080/00221688509499365

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221688509499357

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor