摘要:

In order to investigate the influence of the wind upon the movement of oil slicks on water, experiments were performed using an open channel placed inside a wind tunnel. The channel was a specially designed Ahlborn tank which was arranged so that the direction of flow of the water could be easily reversed, thus enabling the water to be pumped either with or against the direction of the wind. A detailed investigation of the wave motion in the liquid was also performed, since this was clearly an important factor affecting both the velocity and the spreading of the oil.

ISSN:0022-1686    

DOI:10.1080/00221687709499636

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The impingement of turbulent jets on solid boundaries has been studied extensively in the past. It has been established that flow parameters in the impingement region are governed by the impingement height,Hand the initial kinematic momentum flux of the jet. This results from the fact that the jet can be considered as a point source of momentum, whenever it is fully developed before entering the impingement region. Obviously, this finding is suspect in cases of “small” values ofH. An experimental and analytical study of developing jets, impinging on a smooth wall, is presented. Measurements of the velocity field, static pressure in excess of ambient, and wall shear stress are reported. Analysis of the results shows that impingement region flow parameters arc governed by the diameter,dand the intial jet velocity, U()but are independent of H. The impingement region was found to extend 1.2dabove the wall and 1.4dradially from the stagnation point. Semi-empirical methods for predicting the velocity field, static pressure and wall shear stress are developed. The radial growth of the jet from the stagnation point, including the wall jet region, has also been analyzed. Using the quantitative relation governing the stagnation pressure as a criterion, it is proposed tha values ofHless than approximately 5.5dbe considered as “small”: greater than about 8.3das “large”, the range 5.5d≲H≲ 8.3dbeing transitional.

ISSN:0022-1686    

DOI:10.1080/00221687709499637

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The effect of a surface cover (ice-cover) on transverse spreading of a tracer released at a constant and steady rate into a turbulent channel flow is investigated. Velocity, depth and transverse profiles of tracer concentration were obtained at four cross-sections downstream of the tracer source. It is shown that the transverse diffusion coefficient for ice-cover conditions, in a straight rectangular channel, is approximately 50% smaller than the corresponding coefficients for open water conditions. However, when these coefficients are normalised with the product of shear velocity,u*, and hydraulic radius,R, they do not differ significantly. An expression is derived for evaluating the average transverse diffusion coefficient over a channel reach by using concentration measurements at one station downstream of tracer source. This expression is found to give good results.

ISSN:0022-1686    

DOI:10.1080/00221687709499638

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Approximate algebraic solutions are developed using the method of perturbation for spatially varied flow in open channels. The predictions from algebraic solutions are sufficiently accurate for subcritical flows in the range ofyu=0.5 to 1.1 whereyuis the dimensionless depth at the upstream end. Algebraic results are also obtained for mixed flow regime. In the supercritical subregime of the mixed regime flow, the predictions are as accurate as the earlier numerical results given by Li. Analytical results are also produced taking hydraulic friction into account. Experimental results are presented in support of the analytical equations for subcritical regime. The fact that hydraulic friction is appreciably increased in spatially varied flows as noted in some earlier studies is confirmed.

ISSN:0022-1686    

DOI:10.1080/00221687709499639

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

Using the theory of dimensions, it has been established that the dimensionless dispersion coefficient in the transverse direction in meandering channels is a function of the friction factor, meander amplitudeto- width ratio and the width-to-hydraulic radius ratio. An attempt is made to establish the functional relationship by measuring the dispersion coefficients for various values of the above-mentioned parameters. The meandering channels used for this study had realistic bottom configurations which resulted from the scouring and deposition of the sand forming the bottom of the channels in contrast to the rigid bottom channels used in the previous studies. The dispersion coefficients were evaluated using the Generalized Change of Moment Method. Different assumptions for the behaviour of the dispersion coefficient were tested but none exhibited superiority over the others. A numerical method has been developed to solve for the concentration distribution in a meandering channel.

ISSN:0022-1686    

DOI:10.1080/00221687709499640

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

The paper summarises the major results of an investigation of How patterns, turbulence intensity distributions and boundary shear stress distribution in the scour zone of a circular pier under clear water scour conditions.

ISSN:0022-1686    

DOI:10.1080/00221687709499641

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

摘要:

ACCROISSEMENT ET GESTION DES RESSOURCES EN EAUpar J. R. VAILLANT, Editions Eyrollcs, Paris (1977), 61 Ixl. Si. Germain, 75240 Paris, Cedcx 5.

ISSN:0022-1686    

DOI:10.1080/00221687709499642

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221687709499635

出版商:Taylor & Francis Group    

年代:1977

数据来源: Taylor