摘要:

The paper highlights the increasing international public concern relating to hydro-environmental issues and cites examples of some of the water quality problems now being considered by hydraulic engineers on a regular basis. The limitations and restrictions of both physical and numerical hydraulic models are discussed and concern is expressed with regard to the increasing use of numerical models being made by non-specialist engineers or scientists - often with little understanding of hydraulics and numerical methods - to assist in the planning and/or design of water quality related studies. General details are given of numerical models used for flow and water quality concentration predictions in coastal and inland hydraulic basins and two example research projects are described. In the first of these studies comparisons are made between dynamically and non-dynamically linked nested models, with the results indicating that in some circumstances nondynamically linked models can give inaccurate velocity field predictions. In the second example higher order accurate schemes are compared for modelling the advection of abrupt concentration gradients, with computational efficiency and simplicity often being important in hydraulic engineering studies where complex boundaries, often including flooding and drying, can cause added difficulties. Finally, the importance of basic original research is also highlighted, particularly as national and international research funding agencies place increasing emphasis on applied research.

ISSN:0022-1686    

DOI:10.1080/00221689209498893

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The inverse weir problem, that of determining the weir shape in a thin plate weir to comply with a given headdischarge equation is known to depend on the solution ofintegral equation. This has been analytically solved in the past through a reduction to Abel's integral equation, when the discharge law is of the exponential type. Two simple and general numerical solutions to this equation are suggested and their results compared with a number of well known cases from the literature. The numerical method is then applied to the calculation of control weirs for open channels and sedimentation basins.

ISSN:0022-1686    

DOI:10.1080/00221689209498894

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A numerical method which extends traditional one-dimensional characteristic methods for wave propagation to two-dimensional flow is presented for computing dam-break waves. In this method wave interactions and reflections in two dimensions are handled such that complex channel geometries can be easily analyzed. Stability requirements are less stringent than that for explicit finite difference schemes, and body-fitted coordinates are not needed to simulate flow through arbitrary geometries. The computed results compare satisfactorily with experimental data for dam-break flows in a straight channel and along the outer bank of a 180 degree bend.

ISSN:0022-1686    

DOI:10.1080/00221689209498895

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Type III stilling basin, according to U.S.B.R. classification, is conventionally designed like other basins for a single discharge which is usually the design discharge and its performance at other discharges is tested in a hydraulic model. This paper presents a new method of design for a modified type 111 basin over a major range of discharges passing the spillway structure. The modified basin has two rows of friction blocks in contrast to one row in the U.S.B.R. basin, to improve velocity distribution of post-jump subcritical flow in the basin. The design is accomplished by developing a dimensionless semi-theoretical relationship for forced jump height curves (FRJHCS) of the spillway-stilling basin combination and matching the dimensionless tailwater rating curve (TWRC) of the river site with one of the FRJHCS, translating the TWRC verticaly if necessary. So as to avoid preparation of a large family of FRJHCS for the purpose of matching, an alternative method of matching has been developed based on the assumption that both the FRJHCS and TWRCS may be represented by simpler equations of power law form.

ISSN:0022-1686    

DOI:10.1080/00221689209498896

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

New experimental evidence on the statistical structure of turbulent pressure fluctuations at the bottom of hydraulic jumps is brought in this paper in view of its relevance on stability of the linings in stilling basins. Maximum values and the structures of temporal and spatial correlation of the anisotropic field of fluctuating pressures are described. Pressures are measured in the zones of the jump where the uplift load produced on the slabs is maximum for a 5÷10 range of Froude numbers. The results define a novel design criterion for hydraulic engineering practice. It is concluded, upon comparison with analogous results from extensive although seemingly incomplete literature, that the systematic experimentation described herein completes the information needed to characterize the statistical structure of pressure fields past hydraulic jumps.

ISSN:0022-1686    

DOI:10.1080/00221689209498897

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The cavitation damage resistance of stainless steel is investigated using a newly constructed rotating disk apparatus at a relatively high peripheral speed of 65.4 m/s-77.6 m/s, and employing the test specimens with a through-hole to induce cavitation and a range to be eroded in a body. The main results obtained from the measurement of eroded loss weight and the observation of cavitation, are that the velocity exponent which indicates the damage due to cavitation has a tendency to increase with an increase in the peripheral speed, and that the velocity exponent obtained at the constant static pressure shows a larger value than those obtained at a constant cavitation number.

ISSN:0022-1686    

DOI:10.1080/00221689209498898

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The suspended sediment transport problem in open channels is studied from the conservation laws point-ofview. Beginning with equations describing the conservation of mass and momentum of both sediment and water, equations for suspended sediment concentrations in free surface flow are derived. Sediment shear and normal stresses are modeled in a manner similar to that of fluid turbulent stresses. Ordinary differential equations for concentration profiles in the viscous sublayer and in the logarithmic velocity region of a steady uniform flow are developed. Although analytical solutions of these equations were attempted, no closed form solution was found. Therefore, a numerical technique such as the fourth order Runge-Kutta method, is used to solve the concentration profile equations. For lack of data in the viscous sublayer, only the concentration profile for flow with the logarithmic velocity distribution is solved and compared to data.

ISSN:0022-1686    

DOI:10.1080/00221689209498899

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A modified Cebeci-Smith model for the velocity profile in sediment-suspending flow has been developed. Measured velocity profiles from two different data sets have been used as a basis of comparison to determine the degree of validity of the model. The model proves to be an asymptote toward which data trend for low values ofy+.

ISSN:0022-1686    

DOI:10.1080/00221689209498900

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221689209498901

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Hans Albert Einstein: Reminiscences If His Life and Our Life TogetherEdited by Elizabeth Roboz Einstein Iowa Institute of Hydraulic Research, Iowa City, 1991 ISBN 0-37414-033-8 P.B. US $ 12,50.

ISSN:0022-1686    

DOI:10.1080/00221689209498902

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor