Gas-Surface Interactions

Engineers are looking for ways to bring satellite orbits closer to Earth, namely in a very-low-earth-orbit (VLEO). Such orbit brings many benefits, such as reduced cost of launch and improved performance of satellite operation. However, the aerodynamic drag caused by the rarefied existence of atmospheric molecules must be compensated for the longer operation of VLEO satellites. 

As such, aerodynamics near Earth above 100 km in altitude should be analyzed accurately using particle-based simulations. Existing Computational Fluid Dynamics (CFD) will produce inaccurate drag calculations in this highly rarefied regime. Simulating flow conditions in this rarefied regime introduces unique complexities, particularly concerning surface properties influenced by gas-surface interactions (GSI). Therefore, achieving an accurate portrayal of GSI, encompassing factors such as scattering angle, energy accommodation, and potential reactions, becomes essential for precise surface property simulations.

Understanding the aerodynamics of VLEO satellites will allow aerospace engineers to predict the lifespan of satellites and the exact specifications requirements for propulsion methods necessary to compensate for the drag.

• Youngil Ko, Eunji Jun. "Mechanism-specific chemical energy accommodation with finite-rate surface chemistry in non-equilibrium flow." Physics of Fluids 36, no. 9 (2024):096115