About Me

I'm a Research Fellow (post doc) at the University of Warwick interested in turbulence and nonlinear dynamics. I'm fascinated by the unexpected critical behavior in geophysical and astrophysical turbulent systems undergoing a regime change, such as the behavior of three-dimensional turbulence as rotation is gradually increased or ionized plasmas as the magnetic field strength is increased. I am currently transitioning to another fascinating topic relating to bifurcations and out-of-equilibrium phase transitions in turbulence -- the study of transition to turbulence in wall-bounded shear flows.

I am currently working with Dwight Barkley and Laurette Tuckerman on the transition to turbulence in wall-bounded shear flows (more details to come as I begin my work with them...). Previously, during my PhD, I was at the Massachusetts Institute of Technology (MIT) working with Glenn R. Flierl on the turbulent dynamics of gas giant planet atmospheres, particularly interested in the transition region between the deep, ionized interior and outer, neutral region. The other half of my PhD was spent looking at sediment transport statistics and modelling in idealized settings. Work done under the supervision of J. Taylor Perron.

Research

Critical transitions in turbulence

With recent computational advances, careful parameter studies of turbulence transitioning from one regime to the other has become possible. This could be done by varying rotation, layer height, magnetic field strength, or more. These studies show surprising and unexpected behavior: in most cases, turbulent behavior changes sharply at a critical parameter value. Despite more and more studies finding the same critical behavior, an explaination for the existence of these critical points has yet to be found. My work aims to build upon the examples of these critical transitions, but also begin providing understanding for why they might exist to begin with.

Collaborators: Alexandros Alexakis , Kannabiran Seshasayanan, François Pétrélis.

Turbulence in the transition region of gas giant planets and exoplanets

Ionization occurs in the upper atmospheres of hot Jupiter exoplanets and in the interiors of gas giant planets, leading to magnetohydrodynamic (MHD) effects which couple the momentum and the magnetic field, thereby significantly altering the dynamics. In the transition region between the hot, ionized interior and cold, neutral region, one finds moderate temperatures such that the gas is only partially ionized and very poorly conducting. The transition region acts as a bottom boundary for the atmospheric jets seen on the surface, and as a top boundary for the magnetid-field generating dynamo region. It therefore likely affect things like the depths of the jets or the morphology of the magnetosphere. In my work, I use idealized turbulence simulations to understand how the particular characteristics of this region (partial ionization and weak conductivity) affect the dynamics and could therefore influence the formation of jets and more.

Collaborators: Glenn R. Flierl, Keaton J. Burns, Basile Gallet

Sediment transport near the threshold of motion

Sediment transport by wind or water near the threshold of grain motion is characterized by rare but large transport events. This intermittency makes it difficult to relate average bed load sediment flux to average flow conditions, a common approach in the study of sediment transport, or to define an unambiguous threshold for grain entrainment. Although intermittent sediment transport has been observed, previous studies have struggled to explain its presence or reproduce it. Through a series of flume experiments and idealized numerical simulations, my work aims to understand the dynamics of sediment transport near the threshold of motion, to describe the presence of intermittency, and understand its consequences.

Collaborators: J. Taylor Perron, Eric Deal, Jeremy G. Venditti

Publications

Journal publications & preprints

  • "Intermittency properties of a novel lattice model of bed load sediment transport,"
    Benavides, S. J. & Perron, J. T. (In Preparation), 2022.
  • "Effective drag in rotating, poorly conducting plasma turbulence,"
    Benavides, S. J., Burns, K. J., Gallet, B., & Flierl, G. R. (Submitted to the Astrophysical Journal), 2022. [arxiv]
  • "How fast or how many? Sources of sediment transport intermittency,"
    Benavides, S. J., Deal, E., Venditti, J.G., Zhang, Q., Kamrin, K., & Perron, J. T. (In preparation for Geology), 2022.
  • "Grain shape effects in bed load sediment transport,"
    Deal, E., Venditti, J.G., Benavides, S. J., Bradley, R., Zhang, Q., Kamrin, K. & Perron, J. T. (In Review at Nature Geoscience), 2022. [preprint]
  • "Fluid-driven transport of round sediment particles: from discrete simulations to continuum modeling,"
    Zhang, Q., Deal, E., Perron, J. T., Venditti, J. G., Benavides, S. J., Rushlow, M., & Kamrin, K. (Submitted to JGR: Earth Surface), 2022.
  • "Inverse cascade suppression and shear layer formation in MHD turbulence subject to a guide field and misaligned rotation,"
    Benavides, S. J., Burns, K. J., Gallet, B., Cho, Y-K., & Flierl, G. R. Journal of Fluid Mechanics, 2022. [arxiv] [doi]
  • "The impact of intermittency on bed load sediment transport,"
    Benavides, S. J., Deal, E., Rushlow, M., Venditti, J.G., Zhang, Q., Kamrin, K., & Perron, J. T. Geophysical Research Letters, 2022. [preprint] [doi]
  • "Symmetry breaking in a turbulent environment,"
    Alexakis, A., Pétrélis, F., Benavides, S. J., & Seshasayanan, K. Phys. Rev. Fluids, 2021. [arxiv] [doi]
  • "Two-dimensional partially ionized magnetohydrodynamic turbulence,"
    Benavides, S. J. & Flierl, G. R. Journal of Fluid Mechanics, 2020. [arxiv] [doi]
  • "Critical transitions in thin layer turbulence,"
    Benavides, S. J. & Alexakis, A. Journal of Fluid Mechanics, 2017. [arxiv] [doi]
  • "On the edge of an inverse cascade,"
    Seshasayanan, K., Benavides, S. J. & Alexakis, A. Physical Review E, 2014. [arxiv] [doi]

News

  • January 25, 2022 My paper with Keaton Burns, Basile Gallet, James Cho, and Glenn Flierl, Inverse cascade suppression and shear layer formation in MHD turbulence subject to a guide field and misaligned rotation, has finally been published in the Journal of Fluid Mechanics. Take a look here!
  • December 15, 2021 I successfully passed my thesis defense! Send me an email if you are interested in a copy of my thesis. It's bee a great five and a half years at MIT; I've learned and grown so much! I'm so thankful for all of the support I've had from my friends, advisors, and my partner during this time. I will miss Boston, but I am very excited to get going on the next step!
  • December 13, 2021 I can finally officially announce that I have accepted a post doc position at the University of Warwick, where I will work with Dwight Barkley and Laurette Tuckerman on problems related to transition to turbulence in wall-bounded shear flows.
  • August 11, 2020 My first PhD paper with Glenn Flierl, Two-dimensional partially ionized magnetohydrodynamic turbulence, has finally been published in the Journal of Fluid Mechanics. Take a look here!
  • June 15, 2020 I am honored to have been awarded NASA's Future Investigators in NASA Earth and Space Science and Technology (FINESST) fellowship , which will fund me for my last year of my PhD!
  • June 13, 2020 My article with Glenn Flierl on "two-dimensional, partially-ionized, magnetohydrodynamic turbulence" has been accepted by the Journal of Fluid Mechanics for publication.
  • June 1, 2020 Day 1 of summer mentorship! This summer I will be mentoring and working with two undergraduate research interns from MIT, who will be working on a project with Glenn Flierl and I on rotating convection. I look forward to teaching them about fluid dynamics, convection, and numerical simulations, but most importantly I look forward to collaborating with future scientists in the field!