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Prof. Xia Keqing of the Physics Department of The Chinese University of Hong Kong (CUHK) was elected a Fellow of the American Physical Society (APS) for his tremendous contributions to the present experimental knowledge and understanding of turbulent Rayleigh-Benard convection. 

Professor Xia is an expert in the studies of fluid turbulence. Turbulence is everywhere around us, and plays a key role in motions involving fluids. It also influences the way heat is transferred. Turbulent thermal convection is an advanced scientific topic that provides insights into the understanding of complex natural phenomena, such as polarity reversal in geomagnetic field, atmospheric circulation and oceanic circulation, etc. Take polarity as an example. Its stability is of crucial importance to sailing and aviation, as well as to animals such as birds. Millions of living creatures on the Earth will be greatly affected should polarity reversal takes place. 

Professor Xia is honoured to be elected a Fellow of the APS, ‘The Fellowship is a great laurel to me, and it signifies recognition of the hard work by our research team and myself from our professional peers.’ 

Professor Xia discovered that thermal plumes are responsible for the initiation and sustentation of the large-scale circulation (LSC), and that the LSC is driven by the buoyancy of plumes. The LSC in turbulent convection also shares certain characteristics with convections in the mantle and the outer core of the Earth. Professor Xia’s group is the first to systematically study the azimuthal motion of the LSC. Their study also reveals that the flow reversal of the LSC shares some statistical properties with the polarity reversal of the geomagnetic field. As the Earth’s magnetic field is believed to be generated by the turbulent thermal convection of its liquid outer core, these results provide insight into the reversal phenomenon of the geomagnetic field. 

Professor Xia’s work on high Prandtl number heat flux measurement played a pivotal role in resolving a long-standing problem in the field, and his research into the statistical behaviour of thermal plumes shed new light on the Rayleigh-Benard convection problem. The empirical results of his group’s research into polymer solutions have become benchmarks against which various theoretical models have been tested, and have resolved several disputes in this area. Professor Xia has published more than 80 papers in leading international journals and, as a pioneer in his field, has been invited to deliver over 30 lectures and talks at international and mainland conferences. In recognition of his outstanding contributions, he received the prestigious China Higher Education Science and Technology Award (Class II) in 2001, a Croucher Senior Research Fellowship in 2005/06 and the second-class award of the State Natural Science Award in 2009. 

The American Physical Society was founded in 1899, with a mission to advance and diffuse the knowledge of physics through journal publication, scientific meetings and extensive programs in education and public outreach. The Society has over 46,000 members worldwide and all members are eligible for nomination and election to APS Fellowship. With a stringent evaluation by the Fellowship Committee, the election to Fellowship is limited to no more than 0.5% of its membership and is considered one of the highest honours in Physics. 

Over the years, a total of six CUHK professors were elected as APS Fellows. The other five professors include Prof. Yang Chen-ning (1957), Distinguished Professor-at-Large; Prof. Kenneth Young (1999), Pro-Vice-Chancellor and Professor of Physics; Prof. Wu Chi (1999), Chairman, Department of Chemistry and Wei Lun Professor of Chemistry; and Prof. Lin Hai-qing (2003) and Prof. Emily S.C. Ching (2005) of the Department of Physics.