摘要:

Methods are developed for calculation of mean velocity and pressure and mean turbulent kinetic energy, Reynolds tension, dissipation, etc. in turbulent incompressible flow after separation at a sudden increase in the cross-section of a circular duct. One method, based on the concept of effective turbulent viscosity and elliptical equations (because of the recirculation taking place), has allowed prediction of flow conditions from the point of separation to that a long way downstream at which normal flow is restored. Another method is associated more especially with the area in which normal flow is restored after readhesion; as the governing equations in this zone are parabolic, it has been possible to apply models containing Reynolds stress transport equations without the turbulent viscosity concept. The overall calculated data are compared with experimental results determined on an aerodynamics model used to study the effect of the initial boundary layer, Reynolds number and the cross-sectional expansion factor, and with other authors' data.

ISSN:0022-1686    

DOI:10.1080/00221687709499746

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Measurements of shear and pressure distribution on smooth and sand coated two-dimensional triangular elements, simulating ripples and dunes, have been reported. Relations have been derived for the local and average skin shear coefficients in terms of the geometry of the elements and the flow Reynolds number. The local pressure coefficient and the form drag coefficient have been related to the relative roughness and the geometry of the elements. Analysis of the data has shown that the grain resistance of undulated beds calculated by the existing methods is generally greater than the measured average grain resistance of the bad. A large amount of alluvial channel data show agreement with the relation for form drag of the two-dimensional triangular roughness.

ISSN:0022-1686    

DOI:10.1080/00221687709499747

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Starting from a logarithmic main velocity profile, the vertical distribution of the secondary flow in a shallow curved channel is derived. The secondary circulation turns out to have one vertical and two horizontal components. The horizontal component in the main flow direction arises from the longitudinal acceleration of the main flow; the transverse horizontal component is due to the curvature of the main flow. In addition, a numerical method for the computation of the depth-averaged flow field and the bed shear stress (magnitude and direction) is developed. This model has great flexibility of allowable channel geometry. Its results agree better with experimental data if the bed is not flat than in case of a flat bed.

ISSN:0022-1686    

DOI:10.1080/00221687709499748

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

A brief description is given of the physical model and two-dimensional numerical models of the Outer Thames Estuary used in the Third London Airport study. The way in which the numerical model provides essential support for the operation of the physical model is discussed.

ISSN:0022-1686    

DOI:10.1080/00221687709499749

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Radial shear stresses on the surface of curved channel beds due to secondary flow increase with increasing bed roughness and affect the direction of flow of sediment particle motion over a channel bed. By means of an analysis it was shown that this flow direction approaches the tangential diredtion of the flow with increasing bed roughness while flow over smooth curved channel beds shows a stronger deviation from the tangential direction. Accordingly fluid or sediment particles moving at a curved channel bed and originating from the outer wall region reach the inner wall much faster in a flow over a smooth bed than over a rough bed. This analytical result was confirmed by experiments in circular planform channels with fixed beds of varying roughness and also by alluvial bed experiments in circular channels.

ISSN:0022-1686    

DOI:10.1080/00221687709499750

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221687709499751

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

QUASILINEAR HYPERBOLIC SYSTEMS AND WAVESby A. JEFFREY, Published by Pitman Publishing, 1976, 39 Parker St., London WC2B 5PB.

ISSN:0022-1686    

DOI:10.1080/00221687709499752

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221687709499753

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221687709499754

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221687709499745

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor