密集颗粒物料流动特性的多尺度模拟

化工领域常常涉及到密集颗粒系统，其基本特点是系统内颗粒的动态响应特性存在强烈的相关性。建立能准确刻画这一相关性的本构模型是准确预测密集颗粒系统宏观流动特性的基础。本项目首先通过分析应力波动对颗粒物料局部流变特性的影响，建立合理的反映颗粒动态响应特性相关性的非局部流变模型。进而通过开展离散单元法数值模拟，并结合复杂网络理论和扰动分析，确定该模型中相关参数的函数表达式。在此基础上，将该非局部流变模型与连续介质模型耦合，通过计算机模拟，实现对中科院过程所正在研发的大型煤热解移动床反应器冷模装置中固体物料流动特性的系统研究。预期的研究结果将不仅有助于加深对密集颗粒物质复杂宏观动力学响应特性微观/介观机理的认识，也有望为化工领域涉及密集颗粒物质的单元操作如移动床、料斗等的设计与优化提供理论依据。

Dense granular media is commonly encountered in chemical industry. Such system is characterized by the highly relevance of the dynamic response of the particles. Developing suitable constitutive law which can properly depict such relevance is thus fundamental to precisely predict the flow behavior of dense granular assemblies. This proposed project is designed to first establish a non-local rheological model which can account for the relevance of particle’s dynamic response. This is achieved via analyzing the influence of stress fluctuation on the local rheological properties. The values of parameters and the expressions of functions appeared in the model are then identified through a discrete element simulation-complex network theory-perturbation analysis combination strategy. The developed non-local rheological model is then integrated with continuum model to systematically investigate the flow characteristics of granular assembly in a cold model of coal pyrolysis moving bed reactor which is currently being developed in the Institute of Process Engineering, CAS. The anticipated results of present project will not only significantly intensify our knowledge of the micro/meso- mechanism under the complex macro- dynamic response of dense granular materials, but also provide the theoretical base for the design and optimization of chemical unit operations handling dense granular media such as moving bed, silo, etc.