Computation of Atmospheric Entry Flow about a Leonid Meteoroid

Abstract

The flow field is computed around a 1 cm diameter Leonid meteoroid as it enters the Earth's atmosphere at an altitude of 95 km and a velocity of 72 km/s. These conditions correspond to a Knudsen number of 4 and a Mach number of 270. To accurately compute the gas flow, these extreme nonequilibrium conditions require application of a kinetic approach and the present work employs the direct simulation Monte Carlo method. A meteoroid ablation model is included in the computations and is found to play a significant role. The computational results predict that a large region of the flow field is affected by meteoroid ablation that produces an extended wake at high temperature in a sate of thermal equilibrium. These findings are in qualitative agreement with spectroscopic observations of the 1998 Leonid meteoroid shower. The computations indicate that the results are sensitive to the material properties assumed for the meteoroid.