About Me

I'm a fifth year PhD student at the Massachusetts Institute of Technology (MIT) broadly interested in nonlinear dynamics and particularly turbulence. I'm fascinated by the unexpected critical behavior in 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 working under 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 is 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

  • "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. (Submitted), 2020. [conference poster]
  • "Phase transitions in turbulence and the multiplicative-noise universality class,"
    Alexakis, A., Pétrélis, F., Benavides, S. J., & Seshasayanan, K. (Submitted), 2020.
  • "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

  • 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!