摘要:

Lake Saint-Francois is the first fluvial lake downstream of the Great Lakes. Aquatic macrophytes are abundant because of water level stabilization and increased nutrient loads. The influence of plants on flow modification is very important and must be considered in order to simulate hydrodynamic conditions. The spatial distribution of plant species is linked to their instream flow preferences. Several abiotic variables are of importance: light penetration, wave energy, current velocity, nutrients in substrate and physical characteristics of the substrate are controlling the species and their biomass.

ISSN:0022-1686    

DOI:10.1080/00221680009498334

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The paper presents generalisation of the old Prandtl mixing-length hypothesis (MLH) for three-dimensional (3D) flows to provide engineers with a new tool to calculate the mean velocity distribution in turbulent open channel flows. These flows are usually not isotropic, i.e. turbulence may have different length scales in different directions. Hence, at every point of the flow a symmetrical second-order tensor with dimension of length should be given. The components of this tensor are specified based on the structure of the largest turbulent eddies. To demonstrate the usefulness of the proposed model, the Reynolds equations with the new turbulence model are solved and calculated streamwise velocity contours are compared with the measurement results. The importance of turbulent structure (sizes of the largest eddies and their growth rate) in forming the streamwise velocity contours is shown.

ISSN:0022-1686    

DOI:10.1080/00221680009498335

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The unsteady two-dimensional flow of a viscous incompressible fluid in a rectangular cavity, driven by effects of shear and/or buoyancy, is modelled numerically. This physical problem is studied from the viewpoint of obtaining accurate and efficient numerical solutions to the Navier-Stokes equations, applicable to the simulation of convective exchange processes in stratified water bodies, where flows are driven by forced (wind-induced) and/or natural (buoyancy-induced) convection, e.g. in lakes, ponds and reservoirs. The hydrodynamic model, based on the vorticity-stream function formulation, was found to be highly accurate and economical in obtaining iterative solutions to nonlinear coupled systems for a wide range of Reynolds/ Grashof numbers and height/width cavity ratios that can be encountered in natural environments.

ISSN:0022-1686    

DOI:10.1080/00221680009498336

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221680009498337

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This paper describes an application of Large Eddy Simulation methods to the flow in a laboratory-style confluence of parallel channels of unequal depths (Reynolds No. ≈ 13,500), and a natural river channel confluence that also exhibits pronounced bed discordance (Reynolds No ≈ 100,000). The aim is to investigate the formation of periodic flow features inherent in the flow dynamics in river confluences. The laboratory-style confluence predictions are compared with experimental data, and suggest that the simulation was capable of capturing some of the key flow periodicities. The model provides detailed flow and mixing data which help inform understanding of the production and evolution of large scale turbulence features in confluences.

ISSN:0022-1686    

DOI:10.1080/00221680009498338

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This paper constructs, presents and compares four approximate Riemann solvers for use with solving one-dimensional unsteady free surface flows. These solvers are usually the building blocks towards the construction of higher order accurate shock-capturing schemes. Details of the governing equations are presented. One dimensional dam-break flood wave propagations are analysed to demonstrate the applicability and the validity of the Riemann solvers. A treatment of source terms such as friction, slope and non-prismaticity of the channel is also presented. Computed results obtained with these solvers are compared with exact or published numerical solutions to define their characteristics and give an insight into the limitations of the methods, their relative strengths and weaknesses.

ISSN:0022-1686    

DOI:10.1080/00221680009498339

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221680009498340

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

ISSN:0022-1686    

DOI:10.1080/00221680009498333

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor