Snezhana I. Abarzhi

My goals in research are to: explore symmetries of unstable processes; discover concepts cutting through complexity of the problem’s , develop methods of predicting far from equilibrium dynamics, and, ultimately, ensure progress of science, technology and society.

I was born and raised in Vasilkov, a suburb of Kiev, in 1967, in the former Soviet Union, to a Bulgarian-Ukrainian family, the daughter of Ivan I. Abarzhi (a scientist, a doctor of science and professor) and Maria I. Abarzhi (a school teacher and vice-principal). In 1984, at the age of 16, after graduating high school with the gold medal of excellence, I moved to Moscow to pursue my professional education at the Moscow Institute for Physics and Technology (MIPT) – the top school in physics and applied mathematics. I graduated from MIPT summa cum laude, with BS in 1987 and MS in 1990, both in physics and applied mathematics. My MS course also included Landau's course in theoretical physics (‘Theoretical Minimum’) at the Landau Institute for Theoretical Physics and research in condensed matter physics at the Kapitza Institute for Physical Problems.

In 1991-1994 I was a postgraduate student at the Landau Institute for Theoretical Physics, doing research in the field of physical hydrodynamics – i.e., the dynamics of fluids, plasmas, materials – under advisory of Dr. Anisimov (Academy of Sciences Member; first recipient of the Landau-Spitzer award). In 1994, I obtained my PhD in theoretical physics and applied mathematics. My PhD thesis was focused on low-dimensional magnetic systems; it resulted from research extending my Master Diploma in condensed matter and involving collaboration with experimentalists. From this background I learned how to apply general principles of physics and applied mathematics to solve challenging theoretical problems, understand experiments, and interpret data.

My research interests are in: theoretical and applied physics (dynamics of plasmas, fluids, materials); applied mathematics (partial differential equations, boundary value problems, dynamical systems); scientific computing;  data science. My research expertise is in theoretical analysis of unstable processes and their – far from equilibrium, nonlinear, multi-scale, multi-phase, non-local, statistically unsteady – dynamics. The focus is on fluid instabilities, unstable interfaces, interfacial mixing. I contributed to this field by developing physically significant and mathematically rigorous theoretical approaches.

My key results are: the mechanism of interface stabilization and new fluid instabilities; the special self-similarity class and the order in Rayleigh-Taylor mixing; the theory of interface dynamics and the fundamentals of Rayleigh-Taylor instabilities.

My key contribution to the community is founding the scientific program ‘Turbulent Mixing and Beyond’ (TMB). My synergistic activities are: editorial work; serving professional boards, committees, societies; organizing conferences (e.g., TMB conferences since 2007).

Fluid instabilities, unstable interfaces and interfacial mixing are a source of paradigm problems in science, mathematics, and engineering, with broadly ranging applications in nature, technology, industry. Examples include supernovae and molecular clouds, plasma fusion and light-matter interaction, reactive fluids and materials processing, nanofabrication and purification of water. In everyday life, we observe the instabilities and the interfacial mixing when watching water flowing from an overturned cap. This field was founded by Rayleigh (Nobel Laureate 1904), Taylor, Richtmyer, Meshkov. In the past, the problem attracted the attention of Fermi (Nobel Laureate 1938), von Neumann, Chandrasekhar (Nobel Laureate 1983), Birkhoff, and Garabedian.

I developed an original theoretical approach to solve the problem. It is based on group theory and analyzes symmetries and invariant forms of far from equilibrium – i.e. unstable – dynamics.

I founded the group theory approach at the time of my graduate study at the Landau Institute, when I noted that theory of space groups can be applied to describe the dynamics of large-scale coherent structures appearing in Rayleigh-Taylor unstable flows. In 1994-1998, I continued to develop this approach in Rayleigh-Taylor instabilities (as Junior Scientist at the Landau Institute and as Senior Scientist at the High Energy Density Institute of the Academy of Sciences). My work was supported by fellowships from the International Center for Fundamental Physics in Russia (1994-1995) and the International Center for Theoretical Physics in Italy (1995-1998).

I obtained the first analytical solutions for spatially periodic Rayleigh-Taylor flows, linked the multiplicity of the asymptotic solutions to the non-local character of the evolution, and found similarities and differences in Rayleigh-Taylor and Richtmyer-Meshkov dynamics. These results aroused considerable interest in the international scientific community and were recognized with invited lectures at European Physical Society meetings and with awards and fellowships from the Alexander von Humboldt (AvH) foundation and the Japan Society for the Promotion of Science (JSPS). With this support, I further developed my research program as the AvH Fellow at the University of Bayreuth in Germany in 1998-1999 and as the JSPS Fellow at Osaka University in Japan in 2001-2002. In 1999-2001 I got the opportunity to work at the State University of New York at Stony Brook in the USA, and interact with the world-class leader in applied mathematics Dr. Glimm.

The group theory approach revealed a number of fundamental properties of scale-dependent Rayleigh-Taylor and Richtmyer-Meshkov dynamics, including their multi-scale evolution, the universality of three-dimensional flows and the discontinuity of the dimensional crossover. These results explained previous experiments and simulations, while suggesting new directions for interpretation of experimental data and advancing the methods of numerical modeling.

My leadership in this research field was recognized by a fellowship from the Center for Turbulence Research at Stanford University. I worked there as a Senior Fellow (2002-2005), actively interacting with key experts in fluid turbulence computations. Stanford’s research environment inspired me to develop the method of analysis of self-similar interfacial mixing.

In 2005-2013, I continued my work as an Academic Faculty Member at the University of Chicago. This provided me with the opportunity to apply for my own grants (I have been a US citizen since 2010) and to build my research program with the support of the US funding agencies (the National Science Foundation, Air Force Office of Scientific Research, Department of Energy, Department of Defense, and others). Inspiring discussions with the leading figure in theoretical physics Dr. Kadanoff demanded that I succeed in understanding how to place far from equilibrium dynamics of interfaces and interfacial mixing within the general physics context.

Specifically, the analysis of symmetries and invariant forms of self-similar Rayleigh-Taylor mixing led to capturing the physics properties of this process. It found that Rayleigh-Taylor mixing can exhibit order, since it has steeper spectra, stronger correlations, and weaker fluctuations than those in canonical Kolmogorov turbulence. This discovery was endorsed from experiments by Dr. Meshkov (the co-founder of Rayleigh-Taylor and Richtmyer-Meshkov field). It also explained a long-standing puzzle in plasma experiments. It was consistent with the phenomenon of laminarization of strongly accelerated turbulent flows, revealed by world-class leader in turbulence and hydrodynamics Dr. Sreenivasan. This discovery was selected by the US National Science Foundation as a Research Highlight (2013); and the series of works was honored by international awards, including the award of the Academy of Sciences of Russia (2011) and the JSPS invitation fellowship (2011).

This research empowered me to develop a unique educational program on the far from equilibrium dynamics for graduate and professional learning, and to organize a strong research program at Carnegie Mellon University, where I served as Professor of Physics and Mathematics in 2013-2016. My active and productive group involved several graduate and undergraduate students, who conducted theoretical, numerical and data analysis studies, actively published in top journals and presented at reputable conferences.

At the end of 2016 I relocated to the University of Western Australia (UWA) as Professor and Chair of Applied Mathematics, where my responsibilities extended to mentoring specialists at the levels from assistant to full professors, in addition to supervising students. With the support of the local research community and the Australian Research Council, I seeded the top theory expertise, organized an active and productive team, developed frontier research, elaborated the synergistic and educational programs, and launched the experimental program. This machine now runs well and systematically produces significant and intellectually strong results.

In 2020 I was elected Fellow of the American Physical Society. The citation is: ‘For deep and abiding work on the Rayleigh-Taylor and related instabilities, and for sustained leadership in that community.’

The group theory approach enabled breakthroughs in grasping Rayleigh-Taylor dynamics in realistic environments. It yielded the direct derivation of the buoyancy and drag parameters and the exact integration of the governing equations. It discovered the special self-similarity class in Rayleigh-Taylor mixing, whose dynamics can vary from super-ballistics to sub-diffusion depending on the acceleration and retains memory of deterministic conditions for any acceleration. These results explained the existing experiments and simulations, advanced understanding of Rayleigh-Taylor processes in nature, and opened perspectives for technology development.

One important impact of the group theory approach was the mechanism for energy transport and nucleosynthesis in supernovae. It was discovered through the synergy of theoretical physics and applied mathematics with astrophysics. This series of works aroused substantial interest in the scientific community and was recognized with the SciLight of the American Institute of Physics and the cover image in the Proceedings of the National Academy of Sciences of the USA. These works provided the theory tool needed for exploring mathematical and physical aspects of stellar evolution processes, in fruitful interactions with the world-class astrophysicist Dr. Arnett. Another impact was the prediction of new opportunities for plasma control in inertial confinement fusion. They are subjects for consideration at the Discovery Science Program at the National Ignition Facility at the Lawrence Livermore National Laboratory (USA).

The traditions of the Lighthill’ school of applied mathematics inspired me to build the theory of interface dynamics (a phase boundary broadly defined). The theoretical framework is applicable in a broad range of conditions in ideal and realistic fluids. The key outcomes are the inertial mechanism of interface stabilization and new fluid instabilities. In addition to identifying fundamental properties of interface dynamics, these results resolved the prospect of Landau (Nobel Laureate 1962) by showing that the classical Landau’ solution is a perfect mathematical match. This series of works was recognized with invited lectures at the American Physical Society March Meetings (2022, 2019) and with publications in top science journals. The theory of interface dynamics is an engine for examining multi-physics and multi-chemistry problems, in productive collaborations with the world leading figure in materials science Dr. Goddard. The theory predicted instabilities are explored in the experiments by the eminent scientist in physics and chemistry of liquid-liquid interfaces Dr. Schlossman.

In realistic multi-scale processes, a link of theoretical models to observational data is a challenge for data science. We developed a rigorous statistical method to analyze data in the interfacial mixing and in realistic turbulent processes, in inspiring interactions with experimentalists, modelers and data scientists.

This method is harmonious with group theory concepts, with entropy optimization principles, and with turbulence anomalous scaling. Its important outcome is in self-consistent capturing of scale-dependent and self-similar dynamics of the mixing process. The method can be applied broadly in multi-scale processes in nature, technology, laboratory. It can enrich data science at large with predictive approaches for capturing coherence, disorder and chaos in realistic environments.

I became a Guest Professor at California Institute of Technology in 2024 [and was a Visiting Professor at Stanford before that]. It permitted me to closely interact with prominent research groups in science, mathematics, and engineering.

My services to the scientific community reflect the leadership role of theory research. This includes founding the scientific program ‘Turbulent Mixing and Beyond’ and the associated series of international conferences. The program was launched in 2007 to bring together researchers from different areas of science, mathematics, engineering, to focus their attention on fundamentals of the far from equilibrium dynamics, interfaces and mixing. The program’s community currently unites a few thousands of researchers worldwide, from academia, national laboratories and corporations. The series of conferences ‘Turbulent Mixing and Beyond’ cultivated the positive and productive environment in this diverse and competitive community, by encouraging its members to perform at their best. The series of conferences ‘Turbulent Mixing and Beyond’ started in 2007 at the International Center for Theoretical Physics in Italy, and had 17 meetings in 2007-2025, including the 2023 Conference at the Kavli Institute for Theoretical Physics and the 2025 Symposium of the American Mathematical Society in the USA. Google.com returns over ~7,500,000 results for ‘turbulent mixing and beyond’.

In addition to community organization, I actively execute editorial work. I compiled and edited over 20 books and special issues. Many of these publications had a high impact on and established high quality standards in the research field. Especially important is the 2019 Special Feature Issue ‘Interfaces and Mixing’ in the Proceedings of the National Academy of Sciences of the USA. I serve as editor and board member of many highly reputable scientific organizations and journals, including Springer Nature, the Royal Society Publishing, the Institute of Physics Publishing, the Proceedings of the National Academy of Sciences of the USA, the Philosophical Transactions of the Royal Society, the Frontiers Publishing, and others. It is an honor for me to serve the American Physical Society as a Member of the Committee on Scientific Publications.

Unstable interfaces and interfacial mixing couple microscopic kinetics to macroscopic dynamics. These far from equilibrium processes occur commonly in fluids, plasmas, materials, at astrophysical and at atomic scales, from supernova and fusion to climate change and nanofabrication. They are a source of paradigm shifts in science, mathematics and engineering, and are extremely challenging to study. Their solution is required to better understand a broad range of processes in nature and technology, and to address industrial and societal challenges.

My research in far from equilibrium processes is inspired by the classical works of the leading figures in theoretical physics, applied mathematics, fluid dynamics, plasmas, astrophysics. It is linked to and further develops the canonical approaches. It suggests to me the realizable goals: advance knowledge of far from equilibrium dynamics of interfaces and interfacial mixing; develop theoretical methods cutting through the problem’s complexity; and ensure progress of science, technology and society.