Akhilesh S. Tiwari

Education

• Expected Jul 2027
  PhD, Aerospace Engineering

  The University of Texas at Austin · GPA 3.95/4 · Advisor: Prof. David B. Goldstein

  • Dissertation on nozzle shape and array optimisation for plume-directed momentum transfer in space-debris detumbling.
• Nov 2020
  M.Tech, Aerospace Engineering

  Indian Institute of Technology Kanpur · GPA 8.5/10 · Advisor: Prof. Sanjay Kumar
• Jun 2017
  B.Tech, Aeronautical Engineering

  Hindustan University, Chennai · GPA 9.4/10 · Silver Medalist, first in department

Research experience

• Aug 2022 – present
  Graduate Research Assistant — Rarefied gas and vacuum flow modelling

  Computational Fluid Physics Lab, UT Austin

  • Built a coupled continuum→rarefied pipeline (OpenFOAM sonicFoam → SPARTA DSMC) spanning four orders of magnitude in gas density.
  • Ran production DSMC campaigns on 448 MPI ranks on TACC Stampede3, with Knudsen-based adaptive refinement to 15–25M cells and ~48M particles.
  • Quantified the effect of surface temperature and gas–surface interaction models on momentum and energy transfer; developed a hybrid surface-optimisation method giving 46% drag reduction in low Earth orbit.
  • Applying Gaussian-process surrogates and Bayesian optimisation to converging–diverging micro-nozzle design; developing neural-network surrogates for the same problem.
  • Automated a 1,400-simulation campaign with an industry partner using a templated Python framework with a 219-test regression suite.
• Dec 2021 – May 2022
  Graduate Researcher — Computational fluid dynamics

  Ocean Engineering Group, UT Austin · Advisor: Prof. Spyros Kinnas

  • Applied the k–ω SST turbulence model within the VIScous Vorticity Equation solver to oscillatory turbulent flow around a cylinder; validated against an ANSYS Fluent RANS benchmark.
• Apr 2019 – Apr 2021
  Graduate Researcher — Experimental fluid dynamics

  Low-Speed Aerodynamics Lab, IIT Kanpur · Advisor: Prof. Sanjay Kumar

  • Investigated acoustic perturbation of vortex-street transition behind cylinders of varying cross-section in a soap-film tunnel, using interference-based flow visualisation.
  • Designed and built a test bed converting servo rotation into transverse oscillation of a cylinder array, for forced 2-D grid turbulence.

Professional experience

• 2025, 2026
  Graduate Intern

  High Energy Density Science Center, Lawrence Livermore National Laboratory

  • Built a MATLAB–Python pipeline automating HDF data analysis, cutting processing time by 40%.
  • Analysed DANTE soft X-ray spectra to inform hydrodynamic simulations of laser-driven flyer-plate experiments. Invited to return for a second term.
• Jun – Jul 2015
  Summer Intern, Engine Division

  Hindustan Aeronautics Limited, Koraput

  • Designed first-stage low-pressure compressor blade profiles using the mean-line method, implemented in C.

Journal publications

• A. S. Tiwari, A. Moreno, S. Nair, J. Neal, T. C. Underwood, D. B. Goldstein, P. Varghese. “Space debris detumbling via plume impingement: off-pointing, atmosphere, and backscatter effects.” Acta Astronautica 247:691–705, 2026.
• S. Nair, J. Neal, A. Moreno, A. S. Tiwari, et al. “Computational and experimental investigation of nozzle plume impingement for detumbling orbital debris.” Journal of Spacecraft and Rockets, 2026.
• A. S. Tiwari, S. Nair, D. B. Goldstein. “Single- and multinozzle plume impingement to detumble space debris.” Journal of Spacecraft and Rockets, 2024.
• A. S. Tiwari, S. Kumar. “Effect of acoustic perturbation on vortex street transition in a flowing soap film.” Physics of Fluids, 2023.Featured article

Conference papers and presentations

• A. Burtsev, F. Muhammad, A. S. Tiwari, et al. “Effects of modeling measured surface roughness on orbital drag in low Earth orbits.” AIAA SciTech Forum, Orlando, 2026.
• A. S. Tiwari, A. Moreno, et al. “Optimizing space debris detumbling using DSMC: plume impingement dynamics and sensitivities.” AIAA SciTech Forum, Orlando, 2025.
• J. Neal, S. Nair, A. Moreno, A. S. Tiwari, et al. “Computational and experimental investigation of plume impingement for orbital detumbling.” AIAA Aviation Forum and ASCEND, Las Vegas, 2024.
• A. S. Tiwari, S. Kumar. “Dance of a vortex street behind cylinders on different sound notes.” Gallery of Fluid Motion, APS Division of Fluid Dynamics, 2023.
• A. S. Tiwari, S. Nair, D. B. Goldstein. “DSMC simulation of impinging thruster plumes for space debris detumbling.” DSMC Conference, Santa Fe, 2023.
• R. You, A. S. Tiwari, S. A. Kinnas. “Viscous vorticity equation (VISVE) model applied to oscillatory turbulent flow around a cylinder.” SNAME Offshore Symposium, 2022.
• A. S. Tiwari, R. Asokan. “Damage prediction in glass/epoxy laminates under low-velocity impact.” National Conference on Advanced Materials, Chennai, 2015.

Technical skills

Rarefied and vacuum flow

DSMC (SPARTA), variable soft sphere collision modelling, Knudsen-based adaptive mesh refinement, gas–surface interaction and accommodation modelling, continuum-breakdown criteria, free-molecular to continuum regimes

CFD and numerical methods

OpenFOAM (sonicFoam, custom boundary conditions and function objects), ANSYS Fluent, finite volume method, compressible and transient flows, k–ω SST, gmsh

HPC and scientific software

Linux, SLURM, MPI (production runs to 448 ranks), Python (NumPy, SciPy, Jinja2, pytest), multi-GB parallel I/O, ParaView, VTK, Tecplot, MATLAB, LaTeX

Optimisation and data-driven modelling

Bayesian optimisation, Gaussian-process surrogate modelling, Latin hypercube design of experiments, PyTorch, verification and validation

Experimental

Soap-film tunnel, wind tunnel, water tunnel, particle image velocimetry, hot-wire anemometry, LabVIEW

Awards and honours

• 2024–25Charles M. Simmons Endowed Presidential Fellowship in Engineering, UT Austin
• 2025Livermore Lab Foundation Award, Lawrence Livermore National Laboratory
• 2023, 2024Warren A. and Alice L. Meyer Scholarship in Engineering, UT Austin
• 2023Featured Article, Physics of Fluids
• 2023Professional Development Award, Graduate School, UT Austin
• 2021–24Cockrell School of Engineering Scholarship, UT Austin
• 2018–20Postgraduate Scholarship, IIT Kanpur
• 2018All India Rank 46, GATE Aerospace Engineering (98.88th percentile)
• 2017Silver Medalist, Aeronautical Engineering, Hindustan University
• 2015First of 175 students, academic and extracurricular performance, Hindustan University

Teaching

• UT Austin
  • Foundations of Environmental Engineering — taught introductory MATLAB to over 60 students; designed the syllabus and assignments.
  • Compressible Flows — assignment assessment and office hours.
  • Physics Laboratory — laboratory sessions, report assessment, student support.
  • Fluid Mechanics — experimental laboratory sessions.
• IIT Kanpur
  • Engineering Graphics — laboratory sessions for 32 students.
  • Introduction to Aerospace Engineering — support for students from non-aerospace backgrounds.

Professional service and affiliations

• MemberAmerican Physical Society (APS)
• MemberAmerican Institute of Aeronautics and Astronautics (AIAA)