THE INCLUSION OF VORTICAL FLOW STRUCTURES IN ANALYTIC DEPTH-AVERAGED FLOW MODELS OF FLOODING

水淹深度平均流解析模型中包含旋流结构

• 批准号: EP/D50385X/1
• 负责人: Donald Knight
• 金额: $ 12.97万
• 依托单位: University of Birmingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FD50385X%2F1
• 关键词: INCLUSION; VORTICAL; FLOW; STRUCTURES; ANALYTIC

This proposal focuses on the fundamental interaction between longitudinal & planform vorticity in open channel flow. Planform vorticity is a priori excluded from all Reynolds averaged Navier-Stokes (RANS) equation models, but is known to be present in most overbank flows . The Shiono & Knight method of analysis (SKM) is an analytic approach to modelling the influence of vortical structures, mimics 4 key dominant flow processes, avoids the use of 3-D turbulence models and applies at full scale.Despite the value of the SKM approach being confirmed by recent work at HR Wallingford, the original ancillary equations for F (vorticity linked) are known to be inadequate for certain types of non-prismatic floodplains and strongly meandering rivers. One promising approach is to use a two-layer SKM model, splitting vertically the depth-averaging process into two parts, above and below the bankfull stage. This allows a laterally sliced model to be placed on top of another sliced model, with horizontal inter-facial shear added. The lower F values in each slice then represent the streamwise secondary flows, and the upper ones mimic both secondary flows at floodplain/main channel boundaries and plan form vorticity. This produces a much simpler 2-D depth-averaged approach for these types of channel, with all the advantages of SKM, over more complex 3-D turbulence models (LES or RANS). Work is needed to explore this novel theoretical approach, and to assess whether it can be turned into practical spreadsheet tools for use by engineers modelling floods.

本文着重研究明渠流中纵向涡量与平面涡量之间的基本相互作用。平面涡是一个先验排除所有雷诺平均Navier-Stokes（RANS）方程模型，但已知存在于大多数漫滩流。Shiono & Knight分析方法（SKM）是一种模拟涡结构影响的分析方法，模拟了4个关键的主导流动过程，避免了使用三维湍流模型，并适用于全尺寸。尽管SKM方法的价值已被HR Wallingford最近的工作所证实，已知用于F（涡度关联）的原始辅助方程对于某些类型的非棱柱形洪泛平原和强烈弯曲的河流是不适当的。一个有前途的方法是使用一个两层SKM模型，垂直分裂的深度平均过程分为两个部分，以上和以下的平滩阶段。这允许将横向切片模型放置在另一个切片模型的顶部，并添加水平界面剪切。每个切片中较低的F值代表流向二次流，较高的F值模拟漫滩/主河道边界处的二次流和平面形式涡度。这产生了一个更简单的2-D深度平均的方法，这些类型的通道，所有的优势SKM，比更复杂的3-D湍流模型（LES或RANS）。需要开展工作来探索这种新的理论方法，并评估它是否可以变成实用的电子表格工具，供工程师模拟洪水使用。