Yongyun Hwang, Imperial College London will join the Journal of Fluid Mechanics Editorial Board from 2024 as an Associate Editor. To celebrate, Yongyun participated in a Q&A with the Journal.
Journal of Fluid Mechanics: What originally drew you to, or excites you about fluid mechanics?
Yongyun Hwang: I have been fascinated by fluid dynamics, since I was an undergraduate student at Seoul National University, South Korea. It was about how people have approached to study fluid dynamics, where mathematics is used as a primary tool to explain the beautiful natural phenomena observed in our life as well as in many industrial applications.
JFM: Among current research, what papers do you most look forward to reading?
YH: I love reading new discoveries of physical phenomena, with an insightful analysis and sound physical explanation accompanied. Of course, many problems in fluid dynamics are long standing and they require an in-depth research. So, the papers with novel mathematical frameworks providing important physical insights are always exciting to read. Recently, I have become gradually more interested in reduced-order modelling, so the approaches with novel and innovative concepts that can provide an efficient low-dimensional description of complex fluid systems are stimulating to me.
JFM: What are you currently working on that you’d like to tell us about?
YH: My current research is broadly defined in theoretical and computational fluid dynamics to explore and model many exciting phenomena in physical and biological fluid systems. Some topics I have been pursuing recently are dynamical systems analysis and reduced-order modelling for turbulent shear flows, relating coherent structure dynamics to turbulence cascade and dissipation, statistical-state space modelling of turbulence at high Reynolds numbers, and instabilities/transition in thermal convection with cross flows. In the context of biological fluid dynamics, I have been working on continuum modelling of suspensions of motile microorganisms and individual/collective dynamics of active microfilament systems (e.g. cilia and flagella).
JFM: In which areas of Fluid Mechanics research do you expect to see growth in the next ten to twenty years?
YH: Probably the areas related to the main challenges in our time, such as climate change, sustainable energy harvesting/utilisation, and innovative applications of novel data-driven techniques. The traditional areas will probably evolve to explore more complex and practically more relevant scenarios, where the given fluid systems are coupled with density/thermal stratifications, particles, interfaces, complex rheology, compressibility (e.g. high speed), rotations, surrounding structures, electromagnetic fields and complex biological/chemical environments. We have also seen a dramatic growth in research on data-driven approaches over the past decade. Their utilisation will probably be more common and routine, and it will be evolved to distil the existing knowledge basis and newly made observations more thoroughly.
JFM: What are some of the challenges facing the field today?
YH: The traditional areas of fluid mechanics have now become relatively mature, and perhaps only very difficult problems are left. These areas have often been developed by studying some of the key building-block flows in nature: for example, Taylor-Couette flow, boundary layers, convections, homogeneous and isotropic turbulence, mixing layers, and many others. Now is the time that these knowledge accumulated from different types of flows will need to be integrated for more complex and practically relevant scenarios in order to address the main challenges that we are currently facing. To achieve this goal, novel experimental and simulation/computing techniques will need to be developed for these complex fluid systems, together with accurate mathematical models and novel data-mining techniques.
JFM: What drew you to Journal of Fluid Mechanics, or how will your experience and expertise impact the journal?
YH: I have been lucky enough to make an academic journey through various parts of the world through my undergraduate, PhD and postdoctoral studies (Korea, France and UK). Thanks to that, I have been exposed to many exciting perspectives of fluid mechanics from a viewpoint of applied mathematics, physics and engineering, while working on various problems in fluid mechanics (e.g. instabilities, transition, turbulence and pattern formation in classical and biological fluid mechanics). I am hoping that this experience will be useful for the journal’s perspective.
JFM: Why should authors publish in JFM?
YH: The Journal of Fluid Mechanics is the prime journal in fluid mechanics, where the articles containing the most advanced knowledge in the field are published in a very rigorous way. Many great papers in the past have been published in the Journal of Fluid Mechanics, and it probably provides one of the best platforms for fluid dynamicists around the world.
JFM: What are your top 3 papers that were published in the journal last three years?
YH:
Multi-scale invariant solutions in plane Couette flow: a reduced-order model approach, M. McCormack, A. V. G. Cavalieri & Y. Hwang, J. Fluid Mech., 2024, In press.
: Providing a new way to extend the invariant solution concepts of dynamical systems for high Reynolds numbers.
: A new type of reduced-order model employing the concept of ‘statistical state space’ for wall-bounded turbulence at very high Reynolds numbers with data-driven augmentation based on the attached eddy hypothesis of Townsend.
Yongyun is a Reader in Fluid Mechanics in Department of Aeronautics, Imperial College London. He received his BSc and MSc degrees from Seoul National University, Korea and completed his PhD at LadHyX in Ecole Polytechnique in France. He was then a Marie Curie postdoctoral fellow at DAMTP, Cambridge. He has been a faculty member in Imperial College London, since 2013. His research interests are broadly defined in theoretical and computational fluid dynamics, and he specialises instabilities, coherent structures, turbulence, transition and pattern formations in physical and biological fluid systems. Welcome to JFM Yongyun!
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