摘要:

In open channel flow, when a hydraulic jump is forced, an hysteretic behaviour is observed in a particular range of values of the governing variables. In this paper, the catastrophe theory is applied to the study of this phenomenon. The geometry of the cusp catastrophe is used as a descriptive model and, with this basis a calculation procedure is proposed, in which known hydraulic equations are used. The results are experimentally verified for a simplified study case.

ISSN:0022-1686    

DOI:10.1080/00221688709499270

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A methodology for locating the hydraulic controls for layered flow when both the bed elevation and flow width are varying, is presented. The model, based on singular points in the solution of the gradually varying flow equations for the free surface and interface slopes, reviews the basic hydraulic principles behind hydraulic control. A number of different types of control are identified depending upon the depth-discharge relationship at the control, its location relative to the point of maximum constriction and the relationship between the maxima and minima of the internal energy at different locations within the flow. The pair of internal controls for two-layer exchange flow are shown to be a special solution to the model where the exchange flowrate adjusts to match the maximum internal energy at one control with the minimum internal energy at the other.

ISSN:0022-1686    

DOI:10.1080/00221688709499271

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

State space approach may be an useful tool to develop didactic procedures, build up automatic control systems and draw simple simulation models related to flow routing through storm sewer systems. Systems Engineering provides a lot of examples in civil engineering in which general methodology of state space approach fits quite well to the mathematical abstraction of the physical reality.

ISSN:0022-1686    

DOI:10.1080/00221688709499272

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The method of characteristics is used to obtain a solution for a dam-break flood on a sloping channel that is initially dry. It is shown that an exact solution of the St. Vcnant equations does not exist for this problem when traditional representations are used for the bed resistance term, and the solution given herein is obtained by neglecting bed resistance. The calculated solution is compared with experimental results, and it is concluded that the inviscid solution may, in some circumstances, give a more accurate approximation than experimental values obtained from small-scale experiments.

ISSN:0022-1686    

DOI:10.1080/00221688709499273

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The feasibility of' model testing to rate Cut-throat flumes is examined for a particular prototype structure. A model of the structure was built to a scale of I : 7.3 and a rating curve obtained. This rating was tested by examining its prediction of actual storm events against measurements of the same storm events obtained with an HL-flume situated immediately downstream of the prototype structure. The results verify the use of model testing to rate Cut-throat flumes. Examination of the results in the light of previous studies indicates the critical importance of modelling the entrance conditions to the flume as well as the flume itself and reveals the significance of boundary layer scale effects, particular at low flows. The measured piezometric head is shown to be significantly dependent on the elevation of the tapping point and illustrates the need to reproduce the precise tapping point location when model-rating a prototype Cut-throat flume.

ISSN:0022-1686    

DOI:10.1080/00221688709499274

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The effect of suspended sediment on the shape of near-bottom velocity profiles has been investigated theoretically and in the laboratory by a number of authors. However, because the resulting expressions for the profile are generally complicated, such effects are often neglected by engineers analysing measured profiles. We present here a criterion for the conditions of flow velocity and sediment grain-size under which it is permissible to neglect the sediment effects. Where it is not, an estimate of the resulting error in the friction velocity is given. A direct method is presented for obtaining the friction velocity (and hence bed shear-stress) from velocity profiles measured under mobile sediment conditions, which takes account of the suspended sediment effects.

ISSN:0022-1686    

DOI:10.1080/00221688709499275

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

To compute water-surface profiles in steady-state, gradually-varied flows in open-channel networks, an algorithm is presented which allows computation of the flow depths and discharges at all sections simultaneously instead of presently-used, step-by-step procedures. This algorithm is accurate, efficient, and suitable for computer solution, and it may be directly used for computing flows in parallel channels or in channel networks without necessitating graphical plots or other trial-and-error procedures. The Newton- Raphson method is used in the solution algorithm, and the resulting Jacobian matrix is transformed into a banded matrix in order to increase accuracy and to reduce computer time and storage. The governing equations are presented in detail and the solution algorithm is included in its entirety. Example problems are solved for illustration purposes and the results are compared with those obtained by the fourth-order Runge- Kutta method.

ISSN:0022-1686    

DOI:10.1080/00221688709499276

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The Dressier equations with flow resistance and varying channel width for unsteady free-surface flow over curved beds are presented, and a generalized Bresse profile equation for steady curved-flow is derived. Experimental measurements on steady flow over a highly curved spillway demonstrate that the Dressier equations predict the free surface, the bed pressure, and the tangential flow velocity distribution accurately, but the predictions by the classical Saint-Venant equations are almost meaningless. Since both theories require gradual variations in bed geometry, applications to intervals with rapid changes are not valid. For the small intervals of our spillway geometry where the curvature and its derivative vary rapidly, the Dressier solution shows small, but rapid, variations, whereas the measurements indicate a more gradual variation over wider intervals.

ISSN:0022-1686    

DOI:10.1080/00221688709499277

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221688709499278

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221688709499279

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor