Particle swelling is prevalent in many industrial processes involving granular materials. Aiming to explore diffusion-induced expansion behaviours of swellable particles, a diffusion-based model considering distinctive microstructure evolution during swelling is developed and implemented in the discrete element method (DEM). In addition, for comparison, a macroscopic swelling model based on the homogeneous diffusion assumption and a kinetic swelling model are also implemented in DEM. To evaluate the developed DEM models, the size growth and dynamic behaviours of single swellable particles and the particle bed in a rectangular container due to swelling are then investigated experimentally and numerically. It is shown that the microscopic swelling model and the kinetic swelling model can better describe single particle swelling than the macroscopic swelling model. Moreover, the microscopic swelling model can reproduce the phenomena of volume expansion of particles as well as the shrinkage of the core zone simultaneously, as observed experimentally. Furthermore, it is found that the microscopic swelling model is more accurate in predicting expansion of the particle beds, implying that the microscopic diffusion based DEM properly captures the physical mechanisms of particle swelling and can well describe the swelling behaviour of granular materials. It hence could be a useful tool for modelling swellable granular materials. 颗粒膨胀在许多涉及颗粒材料的工业过程中是普遍存在的。为了研究膨胀颗粒的扩散诱导膨胀行为,建立了一种基于扩散的膨胀模型,该模型考虑了膨胀过程中不同的微观结构演化。此外,为了进行比较,在DEM中还实现了基于均匀扩散假设的宏观溶胀模型和动力学溶胀模型。为了对所建立的DEM模型进行评价,对矩形容器中单个可膨胀颗粒和颗粒床在膨胀作用下的尺寸增长和动态行为进行了实验和数值研究。结果表明,与宏观溶胀模型相比,微观溶胀模型和动力学溶胀模型能更好地描述单颗粒溶胀。此外,微观膨胀模型可以同时再现颗粒体积膨胀和核心区收缩的现象,如实验观察到的。此外,微观膨胀模型对颗粒层膨胀的预测更为准确,说明基于微观扩散的DEM能够很好地捕捉颗粒膨胀的物理机制,能够很好地描述颗粒材料的膨胀行为。因此,它可能是一个有用的工具,以模拟膨胀颗粒材料。
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Prof. Chuan-Yu (Charley) Wu is a professor of chemical engineering in the Department of Chemical and Process Engineering at the University of Surrey. UK. Prof. Wu has been the coordinator of two European FP7 and H2020 consortia IPROCOM (2013-2016, €3.8m) and MATHEGRAM (2019-2023, €4.2m), which involve the development of computational tools for pharmaceuticals, and granular materials in general. Prof. Wu is an executive editor for Powder Technology, a leading peer reviewed journal on particle systems. He co-authored a monograph on “Particle Technology and Engineering” published by Elsevier in 2016 and edited two books entitled “Discrete Element Modelling of Particulate Media” and “Particulate Materials: Synthesis, Characterisation, Processing and Modelling” published by RSC publishing. He also edited five journal special issues and published over 100 scientific papers. He has given more than 60 invited presentations and seminars at international conferences, industrial companies and universities worldwide. Prof. Wu is a member of the advisory and editorial board for “Particuology”, “Acta Pharmaceutica Sinica B (APSB) ” and “Journal of Engineering”. Prof. Wu’s expertise lies in discrete element methods, finite element analysis, modelling and simulations, pharmaceutical engineering, particle technology and granular materials. Prof. Wu has been working closely with global companies over the last 20 years in developing advanced numerical modelling techniques for manufacturing pharmaceuticals and fine chemicals. His research has been supported by global pharmaceutical companies including Pfizer, AstraZeneca, Genentech, Sanofi, Janssen and MSD, in addition to EPSRC and EU. 邬传宇(Charley)教授是英国萨里大学化学与过程工程系教授。先后主持两个欧盟项目IPROCOM(2013-2016年,380万欧元)和Maththegram(2019-2023年,420万欧元),这两个联盟涉及制药和一般颗粒材料的计算工具的开发。邬教授是《粉末技术》的执行编辑,这是一份领先的颗粒系统同行评审期刊。2016年,他与人合著了Elsevier出版社出版的《粒子技术与工程》专著,并编辑了RSC出版社出版的《颗粒介质的离散元素建模》和《颗粒材料:合成、表征、加工和建模》两本书。他还编辑了5期杂志特刊,发表了100多篇科学论文。他曾应邀在国际会议、工业公司和世界各地的大学做过60多次演讲和研讨会。吴教授是“微粒学”、“药物学报”(APSB)和“工程学报”的顾问和编委会成员。 邬教授的专长是离散元方法、有限元分析、建模和仿真、制药工程、颗粒技术和颗粒材料。在过去的20年里,吴教授一直与全球公司密切合作,开发先进的数值建模技术,用于制药和精细化学品的制造。他的研究得到了全球制药公司的支持,包括辉瑞,阿斯利康,基因泰克,赛诺菲,杨森和默沙东等。
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