摘要:

First-generation modelling was concerned only with computer adaptations of established, human-friendly methods. In second-generation modelling, on the other hand, methods were used that were more specifically “computer friendly”, even if “human-unfriendly” (e.g., finite-difference and finite-element methods). In third-generation modelling, these methods were incorporated into modelling systems, or “shells”, with which a model of any area could be constructed and run automatically by the system when provided with a suitably-formatted description of the area and its ancillary conditions. During the course of the second- and third-generation developments, however, modelling became an increasingly specialised and hermetic activity, confined for most practical purposes to computational-hydraulics experts. The fourth generation then builds on this earlier development, but in such a way as to provide modelling systems that can be used by professional engineers who are not computational-hydraulics experts.

ISSN:0022-1686    

DOI:10.1080/00221689109498978

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A study of plane thermal-buoyant jets is presented. Experiments were conducted in water, and the results are compared with two integral models, namely a buoyant jet model and a thermal jet model. In the buoyant jet model the equation of state is linear, while in the thermal jet model the equation of state is nonlinear. It is concluded that the buoyant jet model does not adequately predict the behaviour of thermal buoyant jets in a cold water environment. For such flows it is necessary to use the actual equation of state for water.

ISSN:0022-1686    

DOI:10.1080/00221689109498979

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Plane jets in shallow water are often encountered in geophysical flows and engineering applications. The present investigation shows that depending on the distance from the origin scaled by depth, the jets can be divided into three fields with distinct behaviour. A model is then presented allowing discussion of the conditions related to the observed increase or decrease of momentum flux in the vicinity of the orifice. The influence of skin-friction on spreading and entrainment is studied on the basis of existing experimental evidence including the one in the present work.

ISSN:0022-1686    

DOI:10.1080/00221689109498980

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Conductivity probes, as they are proposed by Gibson and Schwarz, are suitable for local concentration measurements in electrolyte turbulent flows. The dependence of the drifting behaviour in NaCl-solutions of such probes from various factors, such as ion concentrations in tap water, temperature, space resolution, etc., has been quantified. Knowing this behaviour errors can be minimized during concentration measurements.

ISSN:0022-1686    

DOI:10.1080/00221689109498981

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A study of air entrainment above an spillway aerator is presented and discussed with a dimensional analysis. We conclude that similitude of air entrainment processes for spillway aerator is not possible between model and prototype. New informations on the aeration region are presented and an analytical solution of the upper nappe entrainment is developed.

ISSN:0022-1686    

DOI:10.1080/00221689109498982

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A quasi two-dimensional model of transient flows in pipes of circular cross-section is developed, using the one dimensional method of characteristics in concentric cylindrical annuli. Lateral velocity components are permitted between adjacent cylinders. The model can nominally incorporate any desired relationship between shear stresses and local velocities. In this paper, it is applied to laminar flows and to a five-region model of turbulent flows.

ISSN:0022-1686    

DOI:10.1080/00221689109498983

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

This paper presents the results of an experimental study on the characteristics of flow in the entrance region of a circular pipe flowing partly full for slopes of 1, 3 and 5%. An analysis of the water surface and velocity profiles in the centerplane indicates the existence of a near-field of the entrance region. At the end of this region, the depth of flow is essentially constant with the velocity in the outer flow (above the boundary layer) having reached a maximum value but the velocity profile is still evolving (in a limited way), associated with the growth of the boundary layer. In this near-field, the flow may be modelled by potential flow with a thin boundary layer of approximately constant thickness. Correlations have been developed for the main characteristics of this near-field.

ISSN:0022-1686    

DOI:10.1080/00221689109498984

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The distribution of turbulence in the wave boundary layer is investigated. Turbulent kinetic energy, eddy viscosity, and other quantities predicted by use of standard one-equation and two-equation turbulence models are compared with experimental data. It is found that the two-equation model gives better results for the eddy viscosity, which is important in connection with the modelling of suspended sediment. The improvements, however, may not be sufficient to justify the extra work involved in a practical application.

ISSN:0022-1686    

DOI:10.1080/00221689109498985

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

AN INTEGRAL EQUATION SOLUTION FOR THE BREAKWATER GAP PROBLEMB. Hunt, Vol. 28, No. 5, 1990, pp. 609-619

ISSN:0022-1686    

DOI:10.1080/00221689109498986

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

AN INTEGRAL EQUATION SOLUTION FOR THE BREAKWATER GAP PROBLEMB. Hunt, Vol. 28, No. 5, 1990, pp. 609-619

ISSN:0022-1686    

DOI:10.1080/00221689109498987

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor