摘要:

Scour immediately downstream of a headcut is analyzed by considering the effect of jet diffusion on sediment detachment. The analytical development results in equations for:

ISSN:0022-1686    

DOI:10.1080/00221689309498814

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The results of an experimental study on the formation and development of sediment bars in straight and meandering channels, are reported. The laboratory observations are used to analyze recently developed linear and nonlinear theoretical models for the formation, geometrical properties, and migration characteristics of alternate bars. The theoretical predictions are found to be in good agreement with the observations of height, wavelength, and celerity of alternate bars. The theoretical conditions for which the suppression of migrating bars in meandering channels takes place, seem to agree qualitatively well with the experimental observations made in the laboratory.

ISSN:0022-1686    

DOI:10.1080/00221689309498815

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

REVIEW OF SHALLOW WATER HYDRODYNAMICSby Tan Wei-yan Elsevier, Amsterdam, ISBN 0-444-98751-7, USS 131,-, Dfl. 255,-.

ISSN:0022-1686    

DOI:10.1080/00221689309498816

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Transport of solid particles in suspension within a turbulent flow has been studied in physical models of settling tanks consisting of a sloping backward facing step and an outlet weir. Mean and fluctuating velocities have been measured by Laser Doppler Anemometry, particularly in the recirculation region generated by the step. Particles injection allowed to determine percentages of outgoing particles as well as the repartition of scdimcntcd particles. These experimental results were used to assess the influence of the geometry on the settling tank efficiency. Experimental results on velocity fields were compared with a vertical two-dimensional turbulence model (VEST code). Results relative to the transport of particles were confronted to the output of an Eulero-Lagrangian three-dimensional model for the simulation of solid particles trajectories (TRAPS code slightly modified). This code uses as input the mean field calculated by VEST. A good agreement has been obtained on outgoing percentages and on the repartition of sedimented particles.

ISSN:0022-1686    

DOI:10.1080/00221689309498817

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The phenomenon of the free overfall, experimentally investigated since the pioneering work of H. Rouse (1933) but not enough known analytically, is studied here assuming the steady flow to be two-dimensional, irrotational and frictionless and accounting for the presence of two free curvilinear boundaries. We derive a more general equation than the known one valid for the flow over a flat bottom. By adopting this equation together with the conservation laws, we can deduce: (a) an equation for the lower profile of the nappe, (b) the value of the brink depth and (c) an equation for the free surface profile of the flow upstream from the brink depth. The results are confirmed by the already available experimental data and by new measurements of the author.

ISSN:0022-1686    

DOI:10.1080/00221689309498818

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In the present study, the flow field of a momentum jet discharged vertically into a wave environment has been investigated. Three distinct processes which increase the dilution rate of the pollutant concentration have been identified by the flow visualization method. They are jet deflection, “wave tractive mechanism”, and wake vortex structure. A highly precise LIF-LDV system was developed to measure simultaneously the two-dimensional velocity field and tracer concentration. The measurements show dramatic variations not only in the longitudinal distribution of the mean jet axis but also in the cross-sectional profiles. A realistic model is also derived to estimate the initial dilution rate under the wave action.

ISSN:0022-1686    

DOI:10.1080/00221689309498819

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Based on the classification of flood waves, two methods are presented for identifying reservoir flood-wave models. These are the magnitude analysis method and quantitative identification method. The methods are applied to two reservoirs in Hunan Province of China, and appropriate flood wave models are accordingly identified for them.

ISSN:0022-1686    

DOI:10.1080/00221689309498820

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The energy concept sheds light upon the hydraulic system that comprises the throttled surge tank, the tunnel and the penstock. The mathematical manipulation of the governing differential equations of water hammer yields an energy (power) equation in point form. By integration with respect to pipe distance, this relation is extended first to an individual pipe, then to the surge-tank system with branching connection. The system energy (power) equation states the relationship between the total (internal plus kinetic) energy, the convective energy, the work done on the system and the energy dissipation. A case study identifies the conversion between the internal and kinetic energy, and quantifies the behaviour and magnitudes of related energy components of the system.

ISSN:0022-1686    

DOI:10.1080/00221689309498821

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

In the numerical modelling of unsteady mixed subcritical and supercritical flows, a great simplification is attained when the algorithmic structure can be kept invariant during the whole course of the computation. This is commonly attained by reducing the influence of the convective momentum term when the flow approaches supercritical conditions, so as to maintain subcritical-like characteristic structures everywhere. The corresponding numerical scheme then becomes a flow-adaptive scheme. The consequences of using such a scheme are investigated and a variant of the momentum equation is identified which reduces the errors introduced through this process to an acceptable minimum.

ISSN:0022-1686    

DOI:10.1080/00221689309498822

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

DEPTH AVERAGED AND MOMENT EQUATIONS FOR MODERATELY SHALLOW FREE SURFACE FLOWP. M. St eff Ier and Y. C. Jin, Journal of Hydraulic Research, Vol. 31, 1993, No. I, pp. 5-17

ISSN:0022-1686    

DOI:10.1080/00221689309498823

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor