Multi-scale modelling of reactive particulate flows

微粒流是许多环境流和人为过程的一部分。在自然界中，陆地滑坡、河流中的沉积物运输、火山爆发的火山碎屑流是许多类型的颗粒流的几个例子。在能源工业中，催化裂化、木材气化、水力压裂和固体颗粒太阳能接收器是典型的应用，掌握颗粒流动是整个过程效率的关键因素。对这类多相流的动力学的正确理解仍然不完整，因为它涉及到分散的固相和连续的周围流体之间复杂的、经常占主导地位的动量、热量和质量传递。由于流动的复杂性，在理解颗粒流动方面取得重大进展对研究科学家和工程师构成了巨大的挑战。***我们在计算和多个尺度（主要是微观和中观）上解决这一挑战。目标应用是存储和转换能量的过程。我们使用PeliGRIFF，这是一个完全并行的平台，为微观和中尺度的颗粒流动提供了强大而有效的模拟方法。本提案的目标是增强PeliGRIFF的数值模型，重点关注(i)非球形颗粒和（ii）颗粒内扩散的传热和传质。一次流配置是固定或流化床反应器。我们计划进行前所未有的模拟，例如，对具有10,000个颗粒的完整反应性3D流化床进行微观模拟。这需要开发和验证新的功能（例如，Sharp-Interface方法来准确捕获流体/颗粒界面上的梯度不连续），并增强我们的模拟工具PeliGRIFF已经令人满意的计算能力。***我们方法的关键特点是平衡先进的数值方法和高度可扩展的代码与深入的物理分析。预期的好处有三个方面：(i)扩展我们对基本水平的反应性颗粒流动动力学的理解，（ii）获得新的动量，热量和质量传递相关性，并将它们纳入中尺度模型，（iii）为加拿大过程工业提供更可靠和准确的数值模拟工具

Particulate flows are part of many environmental flows as well as man-made processes. In nature, land slides, sediment transport in rivers, pyroclastic flows from volcanic eruptions are a few examples of many types of particulate flows. In the energy industry, catalytic cracking, wood gasification, hydraulic fracturing and solid particle solar receiver are classical applications where mastering the particulate flow is a key factor in the overall efficiency of the process. A proper understanding of the dynamics of this class of multiphase flows is still incomplete in relation to the intricate, and frequently dominant, momentum, heat and mass transfer between the dispersed solid phase and the continuous surrounding fluid. Due to the flow complexity, making significant advances in the comprehension of particulate flows constitutes a great challenge for research scientists and engineers.***We address this challenge computationally and on multiple scales (essentially micro and meso). The targeted applications are processes that store and convert energy. We use PeliGRIFF, a fully parallel platform that offers robust and efficient simulation methods for particulate flows at both the micro and meso scales. The goal of this proposal is to enhance the numerical models of PeliGRIFF with a focus on (i) non-spherical particles and (ii) heat and mass transfer with intra-particle diffusion. The primary flow configuration is a fixed or fluidized bed reactor. We plan to perform unprecedented simulations as, e.g., a micro scale simulation of a complete reactive 3D fluidized bed with 10,000 particles. This requires to develop and validate new functionalities (e.g. a Sharp-Interface method to accurately capture the gradient discontinuities at the fluid/particle interface) and to enhance the already satisfactory computing capabilities of our simulation tool PeliGRIFF.***The key feature of our methodology is to balance advanced numerical methods and highly scalable codes with in-depth physical analysis. The expected benefit is three-fold: (i) to extend our comprehension of the dynamics of reactive particulate flow at the fundamental level, (ii) to derive new momentum, heat and mass transfer correlations and to incorporate them in the meso scale model and (iii) to offers more reliable and accurate numerical modelling tools to the Canadian process industry.**