摘要:

Recommended methods for the statistical analysis of extreme waves are presented. Proper data selection is stressed. Data from different seasons and/or of different type or origin should be analysed separately. Use of the peaks over threshold method is recommended. It is advised that a three parameter Weibull distribution is fitted to the observed storm peak data giving due consideration to data censoring.

ISSN:0022-1686    

DOI:10.1080/00221689409498691

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Buoyant spreading phenomena are driven by the buoyant horizontal spreading force that arises from the density difference between the mixed effluent and the surrounding ambient fluid. Such spreading effects, occurring at either water surface, or bottom, or at terminal levels within an ambient density stratification, are significant transport and mixing processes. A model for the lateral buoyant spreading within a currentadvected plume is formulated including several distinct mechanisms: convective spreading with frontal drag effects, interfacial friction, entrainment at the density front, shear flow entrainment, wind-induced entrainment, and surface heat exchange. Also, a criterion, based on a flux Richardson number, has been developed that delineates the transition between the spreading phase and the subsequent passive ambient diffusion regime. The buoyant spreading model is implemented within the Cornell Mixing Zone Expert System (CORMIX). Comparisons with available laboratory and field data support the accuracy and flexibility of the model formulation for analyzing complex and diverse plume patterns.

ISSN:0022-1686    

DOI:10.1080/00221689409498692

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The flow of water in a three-dimensional sand trap is calculated by a numerical model, using a finite volume method to solve the Navier-Stokes equations for three dimensions on a general non-orthogonal grid. Thek-ε turbulence model is used to solve the Reynolds- stress term. The diffusion/convection equation for the sediment concentration is solved giving the sediment concentration in the sand trap. A physical model study carried out to verify the results shows the recirculation zone to be shorter than the numerical model result, but modifications in the turbulence model give better agreement. The sediment concentration calculations compare well with the experimental procedures. The concentration calculated by using the flow field from the originalk-ε model gives 87.1 % trap efficiency, whereas calculation with the more correct flow field gives 88.3 %.

ISSN:0022-1686    

DOI:10.1080/00221689409498693

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Non cohesive sediment at the bottom of a water reservoir can easily be removed with a siphon. Theoretical analysis and experiments show that the mechanism that initiates the removal the grains of the sediment is due not only to the horizontal viscous shear at the top of the sediment, but also to the flow in the sediment it self.

ISSN:0022-1686    

DOI:10.1080/00221689409498694

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Mean flow properties and turbulent characteristics of uniform open-channel flow were experimentally studied in a reasonably steep channel with an erodible gravel bed. A recently developed Acoustic Doppler Velocity Profiler (ADVP) was used to obtain instantaneously the information on the flow profiles. From these measurements, the mean velocities, the turbulence-intensities as well as the Reynolds-stress profiles were obtained.

ISSN:0022-1686    

DOI:10.1080/00221689409498695

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The turbulence characteristics in the hydraulic jumps have been calculated by means of theK-epsilon model which had to be adapted for flow cases of a moving free surface by means of the partially explicit approach. The study includes both free and forced hydraulic jumps with Froude numbers in the range from 2.1 to 7.6. Comparisons of the numerical predictions with the data measured using one-dimensional LDA show that the results correspond well qualitatively, including the mean velocity components and its fluctuations in the flow direction. The results calculated provide insights into the turbulent structure of hydraulic jumps.

ISSN:0022-1686    

DOI:10.1080/00221689409498696

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The jump profile measurements on sloping floor, including the jumps with positive and negative step in an open rectangular channel were conducted. A set of regressed results of experimental data for predicting the length and depth of jumps on sloping floors are proposed. Analysis of sequent depth ratio and length characteristics revealed that the negative step has advantages over the positive with respect to stability and compactness of hydraulic jump. The results in nondimensional form may provide useful information for designing the stilling basin on sloping floor downstream of hydraulic structures.

ISSN:0022-1686    

DOI:10.1080/00221689409498697

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

An analysis - valid for the flow of incompressible fluids through closed and open channels - of the maintenance of the Reynolds stresses, which starts from the Navier-Stokes and mass conservation equations, is applied to steady, two-dimensional, fully developed, low-Reynolds-number turbulent channel flows. The approach adopted considers the Reynolds stresses to depend on the structure of the turbulent components over the entire flow field. As a result of the analysis, the distributions of the mean velocity, the Reynolds stress and the turbulence intensities are found in the inner and outer region in which the shear flow is divided. By matching the solutions in the two regions, new uniform approximations for the distributions are obtained. The derived profiles are compared with available experimental data and the agreement is found to be satisfactory.

ISSN:0022-1686    

DOI:10.1080/00221689409498698

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Integral plume models harbor a fundamental, often significant error because the standard implementation of control volumes, or elements, is inconsistent with the overall geometry of the problem. The error, called the negative volume anomaly, occurs irregularly, being contingent on there being strong bending and large plume diameter. When present it causes entrainment, i.e., dilution, to be overestimated. It is of practical significance because dilution estimates are used to design and assess diffusers.

ISSN:0022-1686    

DOI:10.1080/00221689409498699

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

MECHANICS OF JET SCOUR DOWNSTREAM OF A HEADCUTO. R. Stein, P. I. Julien and C. V. Alonso, Journal of Hydraulic Research, Vol. 31, No. 6, 1993, pp. 723-738

ISSN:0022-1686    

DOI:10.1080/00221689409498700

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor