Multiscale Hypersonic Flow

The design and utilization of space re-entry vehicles have been the subjects of interest by many aerospace engineers and entrepreneurs in recent years. The related technology resulted in SpaceX's success with the Falcon 9 reusable rocket in cutting down the costs of launches and moving a step closer to the commercialization of space travel.

One of the most fundamental challenges to the problem is the high aerothermodynamic load the vehicle is subject to during re-entry. Therefore, it is crucial to accurately analyze the non-equilibrium multiscale hypersonic flow around the vehicle during re-entry in designing the Thermal Protection System. However, the problem is that ground experiments replicating such an environment are costly and error-prone. Therefore, numerical analyses are handy in designing space re-entry vehicles. 

During the Entry, Descent, and Landing (EDL) sequence, a space re-entry vehicle experiences a wide range of flow regimes where Navier-Stokes equations assuming continuum may fail to be valid. For example, at high altitudes, the degree of rarefaction makes Computational Fluid Dynamics (CFD) analysis inadequate in giving accurate results. Furthermore, at lower altitudes where most flow regions are within the range where the Navier-Stokes equation is valid, some local regions, such as interiors of a shock and wall boundary layers, are characterized by strong thermal non-equilibrium. As such, multiscale hypersonic flow requires a particle-based approach for accurate simulations. 

• Eunji Jun, M. Hossein Gorji, Martin Grabe, and Klaus Hannemann. "Assessment of the cubic Fokker–Planck–DSMC hybrid method for hypersonic rarefied flows past a cylinder." Computers & Fluids 168 (2018): 1-13. 

• Eunji Jun, and Iain D. Boyd. "Assessment of the LD-DSMC hybrid method for hypersonic rarefied flow." Computers & Fluids 166 (2018): 123-138. 

• Sanghun Kim, Eunji Jun, "A Fokker-Planck-Based Kinetic Model for Diatomic Rarefied Gas Flows", In DSMC Workshop, 2023. (Sante Fe, NM, USA, Sep. 2023).

• Hanyoung Ryu, Sanghun Kim, Eunji Jun, "Analysis of aerothermodynamics on re-entry rocket booster using DSMC", In The 34th International Symposium on Shock Waves, 2023. (Daegu, Republic of Korea, Jul. 2023)

• Sanghun Kim, and Eunji Jun. "Assessment of various Fokker-Planck methods for hypersonic rarefied flows." In AIP Conference Proceedings. vol. 2996. no. 1. AIP Publishing, 2024. 32nd International Symposium on Rarefied Gas Dynamics (Seoul, Republic of Korea, Jul. 2022).

• Eunji Jun, Iain Boyd, and Jonathan Burt. "Assessment of an all-particle hybrid method for hypersonic rarefied flow." In 51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition. 2013. (Grapevine, TX, USA, Jan. 2013).

• Eunji Jun, Jonathan M. Burt, and Iain D. Boyd. "All‐Particle Multiscale Computation of Hypersonic Rarefied Flow." In AIP Conference Proceedings. vol. 1333. no. 1. American Institute of Physics, 2011. 27th International Symposium on Rarefied Gas Dynamics (Pacific Grove, CA, USA, Jul. 2010).

• Eunji Jun, Jonathan Burt, and Iain Boyd. "All-Particle Multiscale Computation of Hypersonic Rarefied Flow for Mars Entry." In 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition. 2010. (Orlando, FL, USA, Jan. 2010).