Lab profile: Aibing Yu, SIMPAS, Monash University

Click here to explore more Lab Profiles.

Particles are all around. In fact, particles are the second most commonly handled material – after water – in the world. However, our understanding of particulate systems and the interaction forces that occur between particles and surrounding fluids, as well as between particles and walls, is limited. This gap in knowledge is largely due to the difficulties associated with determining the forces that govern the packing and flow behaviour of particles experimentally.

Aibing Yu is hoping to change all that. He has established the Laboratory for Simulation and Modelling of Particulate Systems (or SIMPAS) at Monash University, Australia, as a world-leading research facility in particle science and technology.

As well as heading up SIMPAS, Aibing is Vice-Chancellor’s Professorial Fellow, Pro Vice-Chancellor and President (Suzhou) at Monash University. He has published over 900 articles in particle/powder technology and process engineering and is an Executive Editor of Powder Technology, as well as being on the editorial board of around 20 other journals. Aibing has received various prestigious fellowships and awards including an ARC Federation Fellowship, the Ian Wark Medal and Lecture, and Top 100 Most Influential Engineers in Australia. He is an elected Fellow of Australian Academy of Science, and Australian Academy of Technological Sciences and Engineering.

Aibing talked to Materials Today about his research and future plans…

How long has your team been running?

SIMPAS was established after I joined University of New South Wales (UNSW) in 1992 and largely represents my own research team. Based on this, I established a multidisciplinary research centre at the university in 2000. SIMPAS played a lead role in establishing various initiatives at the national level. For example, I was Deputy Director of the ARC Centre of Excellence for Functional Nanomaterials (2003-2010), Founding Director of Australia-China Joint Research Centre for Minerals, Metallurgy and Materials (2013-2015), and ARC Industrial Transformation Research Hub for Computational Particle Technology (2016-). Recently, sponsored by Jiangsu Industrial Technology Research Institute (JITRI) and local government, we have also established a Specialised Research Institute for Process Modelling and Optimisation in Suzhou, China. SIMPAS moved with me to Monash University in 2014.

How many staff makes up your team?

SIMPAS is currently composed of 15 academic and research staff, along with 35 PhD students. Since its foundation, SIMPAS has graduated over 35 postdoctoral fellows, 70 PhDs and 20 master students.

What are the major themes of research in your lab?

Simulation and modelling of particulate systems is our major research theme. Our aim is to understand the fundamentals governing particulate flow and packing through rigorous simulation and modelling of the particle-particle and particle-fluid interactions at different time and length scales, with application oriented to the mineral/metallurgical/material industries.

The research in SIMPAS lies in five inter-related areas at three levels, as shown in the schematic (Fig. 1), including the development of simulation and modelling techniques (level 1), fundamental studies of particle packing and flow, and the transport properties of static/dynamic particle systems (level 2), and industrial applications (level 3). The three-level classification represents, on one hand, the flow path from R&D capability to industrial application, while on the other highlights the needs from different industries that are the driving force for our research.

How and why did you come to work in these areas?

The challenge of understanding particulate systems first sparked my interest back in the late 1980s when I was doing my PhD on the packing of particles. There is an urgent need to develop innovative techniques to overcome the difficulties of investigating particulate systems. Simulation and modelling, developed on the basis of well-established laws in physics, offers an effective method to do so. With this realisation, I established my team in this area when I started my academic career at UNSW.

What has been your highest impact/most influential work to date?

In terms of research, I have developed a sustained particle- and multi-scaled way to study granular/particulate matter at various time and length scales. This breakthrough has played an important role in developing a step change – and to a large degree, revolutionary– advancement in process modelling and analysis.

In terms of applications, my research impact is significant, having led to multimillion-dollar savings per annum in various industries. In terms of education and training, SIMPAS has trained more than 150 researchers, many of whom are now playing a lead role in academia or industrial R&D.

SIMPAS has conducted over 60 projects supported by the Australian Research Council (ARC), bringing more than A$70M in research funds to UNSW and Monash University.

What facilities and equipment does your lab have?

SIMPAS has developed a sustained and systematic way to study particulate/granular matter at various time and length scales including, for example, the determination of contact forces between particles at an atomic or sub-particle scale, dynamics of a particle system at a particle scale, and performance of an operational unit at a process equipment scale. Our research is mainly computational, so in addition to the use of relatively well known techniques such as Molecular Dynamics (MD) simulation, Lattice Boltzmann Method (LBM), Finite Element Method (FEM), and Computational Fluid Dynamics (CFD), we have also developed a wide range of numerical tools to study particulate systems at the particle scale, mainly based on the so-called Discrete Element Method (DEM) and CFD-DEM (sometimes referred to as Combined Continuum-Discrete Method or CCDM). The tools and research outcomes have been widely used in the design, control and optimisation of industrial processes. An illustration of the use of the various modelling techniques for different purposes in the study of blast furnace iron-making is shown in Fig. 2.

Our work is mainly computational, and intellectually challenging but we are also well equipped with advanced computing facilities (e.g. high performance CPU- and GPU-based computers) at UNSW and Monash. In addition, we have access to computational facilities at the national level (e.g. National Computational Infrastructure in Australia). In the past, we have also built-up experimental facilities of various types, mainly for material characterization and lab-scale experiments for model development and validation.

The same idea can be applied in the study of other ‘particle’ systems. One such example, focused on nanocomposite materials, is shown in Fig. 3. The so-called particles in a nanocomposite experience different governing forces because of the difference in time and length scales. Consequently, different simulation techniques are used for such systems in SIMPAS.  

Do you have a favourite piece of kit or equipment?

I am particularly proud of our CFD-DEM approach in which we employ a traditional CFD model and an innovative DEM model to describe coupled particle-fluid flows at the individual particle scale. This modelling technique is now widely accepted as one of the most effective ways to study the fundamentals of the particle-fluid flows that are widely found in industries. The method has now been further developed to include heat and mass transfer so that particle-scale modelling of complicated industrial multiphase processes is feasible.

What is the key to running a successful lab?

There are different answers from different people with different backgrounds. For me, the answer is simple: a leader must have a big vision, be able to identify important areas for development, and motivate his/her group to work hard toward the goal(s) set. 

How do you plan to develop your lab in the future?

Particle science and technology is multidisciplinary and relatively new. According to Professor Pierre-Gilles de Gennes, the 1991 Nobel Prize laureate in Physics, “Granular matter in 1998 is at the level of solid-state physics in 1930”. At present, solid-state physics is still one of the most active research areas, so granular or particle research is probably still in its infancy. There remains a lot to learn, so it is difficult to predict its future. But one thing is sure: there will be many new developments in theories, physically meaningful models, and advanced research techniques – and particle-scale studies will represent a major trend.

With support of the newly established National Research Facilities - the ARC Research Hub for Computational Particle Technology in Australia and JITRI Research Institute for Process Modelling and Optimisation in China, SIMPAS will grow further. In the coming years, SIMPAS will focus on the quantification of particle-particle and particle-fluid interaction forces under different conditions, the development of a theory to link discrete to continuum modelling, and the development of more robust models and efficient computer codes for designing and optimizing particulate and multiphase processes that are widely used in industries. In the meantime, SIMPAS will put more and more effort to the commercialisation of its research techniques and outcomes, aiming to generate an impact not only in research but also in industrial applications.

Click here to explore more Lab Profiles.

Key publications

1.     A. B. Yu, N. Standish. Estimation of the porosity of particle mixtures by a linear-mixture packing model. Industrial & Engineering Chemistry Research 30 (1991) 1372-1385.

2.     B.H. Xu, A.B. Yu. Numerical simulation of the gas-solid flow in a fluidized bed by combining discrete particle method with computational fluid dynamics. Chemical Engineering Science 52 (1997) 2785-2809.

3.     Y.C. Zhou, B.D. Wright, R.Y. Yang, B.H. Xu, A.B. Yu. Rolling friction in the dynamic simulation of sandpile formation. Physica A 269 (1999) 536-553.

4.     R.Y. Yang, R.P. Zou, A.B. Yu. Computer simulation of the packing of fine particles. Physical Review E 62 (2000) 3900-3908.

5.     A.B. Yu, X.Z. An, R.P. Zou, R.Y. Yang, K. Kendall. Self-assembly of particles for densest packing by mechanical vibration. Physical Review Letters 97 (2006) 265501.

6.     H.P. Zhu, Z.Y. Zhou, R.Y. Yang, A.B. Yu. Discrete particle simulation of particulate systems. Chemical Engineering Science 62 (2007) 3378-3396; and 63 (2008) 5728-5770.

7.     Q.H. Zeng, A.B. Yu, G.Q. Lu. Multiscale modeling and simulation of polymer nanocomposites. Progress in Polymer Science 33 (2008) 191-269.

8.     Z.Y. Zhou, S.B. Kuang, K.W. Chu, A.B. Yu. Discrete particle simulation of particle–fluid flow: model formulations and their applicability. Journal of Fluid Mechanics 661 (2010) 482-510.

9.     Q.J. Zheng, A.B. Yu. Why have continuum theories previously failed to describe sandpile formation? Physical Review Letters 113 (2014) 068001.

10. S.F. Wang, M.S. Liu, L. Kong, Y. Long, X.C. Jiang, A.B. Yu. Recent progress in VO₂ smart coatings: Strategies to improve the thermochromic properties. Progress in Materials Science 81 (2016) 1-54.