Computational Methods for Multiscale Turbulent Reacting Flows

提出的研究的目的是开发计算方法的多尺度建模框架内的湍流反应流。该框架是基于混合粗粒度和细粒度（分别）。模拟的基础上大涡模拟（LES）和随机低维模型，一维湍流（ODT）模型。ODT模型的目的是捕捉湍流和分子传输和化学/热释放之间的耦合。该框架已开发的PI燃烧直接模拟亚网格尺度的物理与化学的相互作用，但是，它可以很容易地有更广泛的应用多尺度驱动流涉及三维确定性解决方案与低维随机解。这里提出的工作扩展了模型配方，以解决多尺度计算工具的发展，耦合两个解决方案。这些方法包括基于物理的匹配LES和ODT之间的过滤亚网格尺度应力以及基于小波变换的多分辨率方法的实施。将制定和实施数据同化策略，以管理从随机解到高阶确定性LES解的统计转移。最后，策略，以加速化学动力学和分子输运的整合将被调查，以提高混合LES-ODT制定的计算效率。各种配方将验证直接数值模拟（DNS）。提出的努力解决了一个新的模拟框架，研究燃烧流。化石燃料和新型燃料的燃烧构成了狮子？随着计算资源和技术的不断扩展，模拟燃烧流的能力最终可以取代建造昂贵的发动机原型，加快设计到生产的过程，并有助于减少污染物和温室气体的产生。燃烧模拟很复杂，因为需要对从分子尺度到设备尺度的复杂物理学进行描述;研究人员和他的同事将开发多尺度策略，通过混合模拟来模拟燃烧流，这些混合模拟旨在解决不同范围内的物理问题。规模。结合的结果是这些模拟的结果，在计算上有效的策略，以代表广泛的范围内的规模在燃烧流的自举过程。这项工作的大部分需要深入了解燃烧流的物理特性以及对能源和环境的影响;但是，这项工作的其他方面利用了信息技术的进步（包括获得超级计算资源，软件的进步）和计算数学。

The objective of the proposed research is to develop computational methods within a multiscale modeling framework for turbulent reacting flows. The framework is based on hybrid coarse-grained and fine-grained(resp.) simulations based on large-eddy simulations (LES) and a stochastic low-dimensional model, the one-dimensional turbulence (ODT) model. The ODT model is designed to capture the coupling between turbulent and molecular transport and chemistry/heat release. The framework has been developed by the PI for combustion to directly model subgrid scale physics associated with turbulence-chemistry interactions; but, it can easily have broader applications for multiscale driven flows involving 3D deterministic solutions with low-dimensional stochastic solutions. The work proposed here extends the model formulation to address the development of multiscale computational tools to couple the two solution schemes. The approaches involve physics-based matching of filtered subgrid scale stresses between LES and ODT as well as the implementation multiresolution methods based on the wavelet transform. Data assimilation strategies will be formulated and implemented for managing the transfer of statistics from the stochastic solution to the high-order deterministic LES solution. Finally, strategies to accelerate the integration of chemical kinetics and molecular transport will be investigated to improve the computational efficiency of the hybrid LES-ODT formulation. The various formulations will be validated with direct numerical simulations (DNS).The proposed effort addresses a novel simulation framework to study combustion flows. The combustion of fossil and novel fuels make up the lion?s share of energy consumption in the US and abroad; and the ability to simulate combustion flows, with expanding computational resources and know-how, can eventually replace building expensive prototypes of engines, and speed up the design-to-production process, and help mitigate the generation of pollutants and greenhouse gases. Combustion simulation is complex, because an account of complex physics from the molecular scale to the device scale is required; the investigator and his colleagues will develop multiscale strategies to simulate combustion flows through hybrid simulations that are designed to addresses physics at different ranges of scales. The combined outcome is a bootstrapping process for these simulations that results in computationally efficient strategies to represent the broad ranges of scales in combustion flows. Much of the effort requires insight to the physics of combustion flows and energy and environmental implications; but, other aspects of the effort draw upon advances in information technology (including access to supercomputing resources, advances in software) and computational mathematics.