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

随着快速增长的能源需求和环境问题，利用先进的燃烧技术和替代燃料正获得越来越多的关注。然而，与这些新兴的能量转换策略相关联的是，越来越需要关于反应速率、输运性质和宏观水平上的系统表征所需的其他本构关系的准确和可靠的信息。由于我们目前关于这些本构关系和速率系数的知识主要依赖于实验，目前迫切需要用计算研究来补充这些研究，以便扩展目前的模拟工作，并能够充分说明发生在宏观尺度和原子尺度上的过程之间的耦合。这项探索性研究计划的目标是发展一种非均匀多尺度方法（HMM）化学反应系统。在这个HMM公式中，宏观模型由质量、动量、能量和物质的守恒方程描述，而本构关系、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评估。为了证明这种方法的潜力，被认为是一个典型的燃烧问题。为了促进HMM的成功应用，本研究将系统地讨论与微观-宏观耦合的尺度桥接算子的严格定义以及HMM模型复杂性的必要降低相关的基本科学问题。如果成功的话，所提出的探索性研究计划，使复杂的燃烧系统的整体调查，并消除依赖于不完整和不可靠的本构关系的信息。解决计算模型复杂性降低的数学发展将是关键，使HMM应用到复杂的燃烧问题。更广泛地说，HMM模型的研究是通用的，可以应用于广泛的工业问题，包括催化过程，流化床燃烧，表面氧化，以及其他关于详细化学机理和其他本构关系的信息不可用的问题。这项研究的更广泛的影响来自于对化学动力学和燃烧过程的更好理解，这将补充实验研究。研究计划紧密结合教育和推广活动。具体而言，关于燃烧和推进的课程将辅之以关于替代能源系统的讲座。此外，本科生的研究活动将在学年和夏季组织。在这些研究活动中，学生将研究与可持续能源发电相关的主题，并解决基础热力学和燃烧物理学的基本问题。

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.