EAGER: Development of a Heterogeneous Multiscale Model as Scale-Bridging Method for Chemically Reacting Systems

随着能源需求的快速增长和对环境的关注，先进燃烧技术和替代燃料的利用越来越受到重视。然而，与这些新出现的能量转换策略相关联的是，越来越需要关于反应速率、输运性质和其他本构关系的准确和可靠的信息，这些信息是在宏观水平上表征系统所需的。由于我们目前对这些本构关系和速率系数的了解主要依赖于实验，因此迫切需要用计算研究来补充这些研究，这些研究扩展了当前的建模工作，并能够完全解释发生在宏观和原子尺度上的过程之间的耦合。这一探索性研究计划的目标是开发一种用于化学反应体系的非均相多尺度方法(HMM)。在这种隐马尔可夫模型中，宏观模型由质量、动量、能量和物种的守恒方程描述，本构关系、反应速率和其他宏观量的不完整或不可靠的数据由详细的原子模型来评估。为了证明这种方法的潜力，我们考虑了一个正则燃烧问题。为了促进隐马尔可夫模型的成功应用，本研究将系统地解决与微观-宏观耦合的尺度桥算子的严格定义以及必要的降低隐马尔可夫模型复杂性相关的基本科学问题。如果成功，拟议的探索性研究计划将使复杂燃烧系统的整体调查成为可能，并消除对不完整和不可靠的本构关系信息的依赖。解决降低计算模型复杂性的算法开发将是使HMM应用于复杂燃烧问题的关键。更广泛地说，这项关于隐马尔可夫模型的研究是一般性的，可以应用于广泛的工业问题，包括催化过程、流化床中的燃烧、表面氧化以及其他没有关于详细的化学机理和其他本构关系的信息的问题。这项研究的更广泛的影响源于对化学动力学和燃烧过程的更广泛的理解，这将补充实验研究。该研究计划将教育和外展活动紧密结合在一起。具体来说，关于燃烧和推进的课程将由关于替代能源系统的讲座来补充。此外，还将在学年和暑期为本科生组织研究活动。在这些研究活动中，学生将致力于与可持续能源发电相关的主题，并解决基本热力学和燃烧物理的基本方面。

1139338IhmeWith the rapidly growing energy demand and environmental concerns, the utilization of advanced combustion technologies and alternative fuels is gaining increasing attention. However, associated with these emerging energy-conversion strategies is an increasing need for accurate and reliable information about reaction rates, transport properties, and other constitutive relations that are required for the system characterization on a macroscopic level. Since our current knowledge about these constitutive relations and rate coefficients primarily relies on experiments, a critical need exists to complement these studies with computational investigations that extend current modeling efforts and are able to fully account for the coupling between processes occurring on macroscopic and atomistic scales.The objective of this exploratory research program is the development of a heterogeneous multiscale method (HMM) for chemically reacting systems. In this HMM-formulation, the macroscopic model is described by the conservation equations for mass, momentum, energy, and species, and incomplete or unreliable data for constitutive relations, reaction rates, and other macroscopic quantities are evaluated from a detailed atomistic model. To demonstrate the potential of this approach, a canonical combustion problem is considered. To facilitate the successful application of HMM, fundamental scientific issues associated with the rigorous definition of scale-bridging operators for micro-macro coupling and the necessary reduction of the HMM model complexity will be systematically addressed in this research. If successful, the proposed exploratory research program enables the holistic investigation of complex combustion systems, and eliminates dependencies on incomplete and unreliable information about constitutive relations. Algorithmic developments addressing the reduction of the computational model complexity will be critical to enable the HMM application to complex combustion problems. More broadly, this research on the HMM model is general and can be applied to a wide range of industrial problems, including catalytic processes, combustion in fluidized beds, surface oxidation, and other problems for which information about detailed chemical mechanisms and other constitutive relations are not available.The broader impact of this research arises from the improved understanding about chemical kinetics and combustion processes, which will complement experimental investigations. The research program closely integrates education and outreach activities. Specifically, courses on combustion and propulsion will be complemented by lectures on alternative energy systems. In addition, research activities for undergraduate students will be organized during the academic year and the summer. In these research activities, students will work on topics related to sustainable energy generation and address fundamental aspects on basic thermodynamics and combustion physics.