摘要:

The flow field and erosion pattern of continuous and pulsating impinging jets has been studied experimentally. The mean velocity field as well as turbulent and pulsation components, wall pressure and wall shear stress distributions were investigated in an axisymmetric air jet impinging upon a rough wall. The results show how harmonic velocity pulsations at the nozzle affect both the mean and the turbulent flow field. Corresponding erosion tests with a vertical water jet impinging upon a uniform sand bed exhibited under certain conditions a greatly enhanced erosion rate. The increase in erosion capacity due to pulsation seems to be due to both the changes in the mean flow field and to the greatly increased lateral correlation of the velocity field in the impinging region.

ISSN:0022-1686    

DOI:10.1080/00221687909499582

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Experiments arc described in which the occurrence of flow separation under hydraulic jumps is studied as a function of Froude number, Reynolds number and condition of inflow. It is found that separation occurs quite generally, that it extends beyond the conventional downstream end point of the hydraulic jump, and that its severity tends to increase with increasing Froude number and to decrease with increasing Reynolds number. In any case, however, the areal extent and thickness of the separation cavity is very much larger for jumps with undeveloped inflow than it is for their counterparts with fully developed inflow.

ISSN:0022-1686    

DOI:10.1080/00221687909499583

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

A study is made of the thermal structure in stratified water by using a onc-dimcnsional two layer mathematical model. The model accounts for the nonlinear interaction between the large flux of thermal diffusion and the buoyancy gradients produced by atmospheric and solar surface heating. The objective is to determine the water temperature at any time and position by using available meteorological data and the physical characteristics of the water body. Calculated water temperatures are compared with the measured values. The comparison shows the expected similarity.

ISSN:0022-1686    

DOI:10.1080/00221687909499584

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

This theoretical study of the effect of viscoelastic material properties of a pipe conveying one-dimensional, non-stationary flow shows that, in addition to exponential attenuation of wave fronts, the disturbance is transformed into a diffusion front whose thickness increases as √t, and which propagates at a velocity corresponding to the retarded elasticity of the pipe material [E(∞)]. The behaviour of pressure disturbances in the special case of water-hammer resulting from sudden closure of a valve is illustrated by a numerical application based on the characteristics method.

ISSN:0022-1686    

DOI:10.1080/00221687909499585

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Derivations of distributions of diffusivity, flow velocity, and sediment concentration over the flow depth were made for a generalized normalization of the relative distance from the flow boundary. Boundary condition restraints suggest a normalization function with a finite lower limit and an infinite upper limit. In analytical considerations, the distribution functions were discussed relative to an unspecified mean turbulent diffusivity. An analysis of the distributions was made in terms of their limits at the channel boundary and the free surface (or top of the boundary layer).

ISSN:0022-1686    

DOI:10.1080/00221687909499586

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

COMPUTATIONAL HYDRAULICS - ELEMENTS OF THE THEORY OF FREE SURFACE FLOWSby M. B. ABBOTT Pitman Publishing Ltd., 39 Parker Street, London WC 2B 5PB, England. Price £ 22.50 non-net.

ISSN:0022-1686    

DOI:10.1080/00221687909499587

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221687909499581

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor