Computational Framework for Multi-Scale Environmental Modelling

多尺度环境建模的计算框架

基本信息

批准号：
NE/H002847/1
负责人：
Matthew Piggott
金额：
$ 24.34万
依托单位：
Imperial College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2010
资助国家：
英国
起止时间：
2010 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FH002847%2F1
关键词：
Computational Framework Multi Scale Environmental

项目摘要

Convection is one of the most challenging problems in atmospheric science today. It covers highly energetic processes, like volcanic eruptions or biomass burning plumes, as well as fields of cumulus clouds or single deep thunderclouds. Standard atmospheric models, such as those used in weather forecasting or climate prediction, are generally not able to resolve the scales involved in convective activity. While cloud or plume sizes may well reach the 1km scale in the horizontal and 10km scale in the vertical, key processes, such as turbulent mixing that lead to extremely important entrainment (mixing environmental properties into the convective column) are of the scale of a few to tens of metres. Such convective processes are often responsible for fast vertical transport of pollutants from the boundary layer to higher atmospheric layers (in volcanic eruptions, or very deep convective clouds, up to the stratosphere), and therefore their correct simulation is highly crucial. Similarly, less vigorously convective but highly turbulent flows in complex topographies (urban or mountainous environments) are important for the dispersion of hazardous chemical species or for the development of wild fires. Such situations are challenging for the current generation of environmental numerical models. The overall purpose of this project is to couple and optimise two existing computational models (Imperial-FLUIDITY and Cambridge-ATHAM). ATHAM is a high-resolution atmospheric model with physical parameterisations for a wide range of plume and cloud relevant applications. ATHAM has successfully simulated atmospheric processes with high spatial resolution within a limited area for problems where topography and the interaction with the flow outside the computational domain are of secondary importance. FLUIDITY contains state-of-the-art parallel adaptive mesh methods that are able to optimally resolve flows, whilst being able to represent key force balances (geostrophic and hydrostatic) exactly which is important for accuracy and stability, and has been developed in its oceanographic guise of ICOM. FLUIDITY lacks the physical parameterisations for atmospheric problems that ATHAM will supply; however, it provides a general framework for CFD problems for a wide range of computational domains and resolutions. ATHAM-FLUIDITY will combine the best elements from both models. That is, the flexible adaptive mesh and balance maintaining finite element methods of FLUIDITY and the advanced physical models of ATHAM, allowing a new range of problems associated with global atmospheric models to be investigated. An important example is convection, which often develops within frontal systems that are part of the large-scale flow with topography and differential heating due to surface inhomogeneities often providing the perturbation that can trigger convection. The combined model will be able to capture large-scale flows as well as fine-scale features in areas of interest allowing a more efficient interaction of scales in one single model. Over the last decade, the programming paradigm has changed from structured to modular and object-oriented programming, in which any set of modern languages may be widely used. Therefore, combining a number of open-source codes and libraries with the physics and advanced numerical technologies contained within FLUIDITY and ATHAM offers an excellent opportunity to develop the combined ATHAM-FLUIDITY model as a next-generation environmental flow model. The main advantages of the resulting open-source model will be: (a) flexibility of the problem formulation; (b) multi-physics modelling to optimally represent the physics using parallel mesh adaptivity and; (c) modular design of the advanced component technologies (e.g. CAD-geometry and mesh generation, linear and non-linear solvers etc). ATHAM-FLUIDITY will be linked produce computational results that are more realistic and accurate than the existing software codes.

对流是当今大气科学中最具挑战性的问题之一。它涵盖了高能过程，例如火山爆发或生物质燃烧羽流，以及积云或单一深层雷云的区域。标准大气模型，例如用于天气预报或气候预测的模型，通常无法解析对流活动所涉及的尺度。虽然云或羽流的大小很可能达到水平方向 1 公里规模和垂直方向 10 公里规模，但关键过程（例如导致极其重要的夹带（将环境特性混合到对流柱中）的湍流混合）的规模只有几个至数十米。这种对流过程通常导致污染物从边界层快速垂直输送到更高的大气层（在火山喷发或非常深的对流云中，直到平流层），因此正确的模拟非常重要。同样，复杂地形（城市或山区环境）中对流强度较低但高度湍流的流动对于危险化学物质的扩散或野火的发展非常重要。这种情况对于当前一代的环境数值模型来说是具有挑战性的。该项目的总体目的是耦合和优化两个现有的计算模型（Imperial-FLUIDITY 和 Cambridge-ATHAM）。 ATHAM 是一种高分辨率大气模型，具有物理参数化，适用于各种羽流和云相关应用。 ATHAM 成功地在有限区域内以高空间分辨率模拟了大气过程，解决了地形和与计算域外气流的相互作用次要的问题。 FLUIDITY 包含最先进的并行自适应网格方法，能够最佳地解析流动，同时能够准确地表示关键的力平衡（地转和静水），这对于准确性和稳定性非常重要，并且已在海洋学中开发国际博物馆协会的幌子。 FLUIDITY 缺乏 ATHAM 将提供的大气问题的物理参数化；然而，它为各种计算领域和分辨率的 CFD 问题提供了通用框架。 ATHAM-FLUIDITY 将结合两个模型的最佳元素。也就是说，FLUIDITY 的灵活自适应网格和平衡保持有限元方法和 ATHAM 的先进物理模型，允许研究与全球大气模型相关的一系列新问题。一个重要的例子是对流，它通常在锋面系统中发展，锋面系统是大规模流动的一部分，由于表面不均匀性而导致地形和加热差异，通常会提供可以触发对流的扰动。组合模型将能够捕获感兴趣区域中的大规模流量以及精细尺度特征，从而允许在一个模型中更有效地进行尺度交互。在过去的十年中，编程范式已经从结构化编程转变为模块化和面向对象的编程，其中可以广泛使用任何一组现代语言。因此，将大量开源代码和库与 FLUIDITY 和 ATHAM 中包含的物理和先进数值技术相结合，为将 ATHAM-FLUIDITY 组合模型开发为下一代环境流模型提供了绝佳的机会。由此产生的开源模型的主要优点是： (a) 问题表述的灵活性； (b) 多物理场建模，使用并行网格自适应性来最佳地表示物理场； (c) 先进组件技术的模块化设计（例如 CAD 几何和网格生成、线性和非线性求解器等）。 ATHAM-FLUIDITY 将产生比现有软件代码更真实、更准确的计算结果。