Current Research Areas

These are areas of research I am actively working on! For a comprehensive list of previous work, please see my CV page.

Hypersonic Aerothermodynamics

Objects and vehicles moving much faster than the speed of sound through an atmosphere experience a range of complex, highly-coupled gas dynamics effects that fundamentally alter the way engineers approach vehicle design. If a vehicle moves at a speed of at least five times the speed of sound, it is defined as ‘hypersonic’. At hypersonic speeds, the vehicle compresses the surrounding atmosphere via a shock, leading intense heating of the gas and the surface of the vehicle. The physics of this flowfield must be well understood in order to optimize vehicle design or develop advanced technologies. Some examples of hypersonics flows include a spacecraft entering a planet’s atmosphere, satellites orbiting very low Earth orbit, and space debris disposal via atmospheric re-entry.

My Ph.D. work consisted of studying partially ionized hypersonic flows. At sufficiently high hypersonic speeds, a fraction of gas is ionized via the shock layer to form a plasma. These ionized species carry electric charge, leading to the formation of electric fields. Research in hypersonic plasmas has direct application in mitigation of radio communications blackout, detection of radiation signatures of hypersonic flight, magnetohydrodynamic flow control and propulsion, and more.

• Petrusky, M., Boyd, I.D. (2026). Evaluation of the Ambipolar Diffusion Approximation in Partially Ionized Rarefied Hypersonic Flows. Submitted, preprint available at arXiv:2608.12498v1.
• Petrusky, M., Boyd, I.D. (2026). Discrete-Velocity Simulation of a One-Dimensional Hypersonic Stagnation Streamline. Journal of Thermophysics and Heat Transfer, 40(3). DOI: 10.2514/1.T7373

Kinetic Modeling Methods

To categorize a fluid flow, engineers often compare the length scale of a physical process of interest to the average distance between particle collisions. When the average distance between particles is comparable to or greater than the physical process of interest, the gas is considered ‘rarefied’. Study of rarefied gas flows necessitates the use of kinetic modeling methods, as traditional computational fluid dynamics codes do not accurately capture flow physics. Research in kinetic modeling methods often centers on reducing computational cost or developing models to capture new phenomena. I have expertise in two types of kinetic modeling methods: Direct Simulation Monte Carlo, a stochastic particle-based approach, and discrete-velocity solvers, which numerically solve the Boltzmann equation for a discretized velocity distribution function. Some applications I am interested in include very low Earth orbit, hypersonic aerothermodynamics, and low temperature plasmas.

• Petrusky, M., Boyd, I.D. (2026) Evaluation of the Ambipolar Diffusion Approximation using an Eulerian Boltzmann-Poisson-BGK Solver. In: Grabe, M., Oblapenko, G., Torrilhon, M. (eds) Rarefied Gas Dynamics. RGD 2024. Springer Aerospace Technology. Springer, Cham. DOI: 10.1007/978-3-032-00094-1_65
• Petrusky, M., Boyd, I.D. (2025). A Novel Stagnation Streamline Model for Discrete-Velocity Simulation of Hypersonic Flows. AIAA AVIATION FORUM AND ASCEND 2025, AIAA 2025-3475. DOI: 10.2514/6.2025-3475