Micrometeoroid Entry as a Fluid-Structure Interaction Problem: A Coupled DSMC-FEM Approach

Earth is impacted by tens of thousands of tons of meteoric material every year, with the bulk of these impactors being micrometeoroids, or meteoroids on the order of a gram, or smaller. Micrometeoroids are primarily studied using radar, where their properties are inferred from the signal-to-noise ratio of radar signals that are reflected off the surrounding plasma. The entry of micrometeoroids into the atmosphere is a complex physical process, which includes ablation, rarefied hypersonic flow, and plasma formation. To better understand this phenomenon, we formulate micrometeoroid entry as a fluid-structure interaction problem in rarefied flow. We develop and apply a partitioned approach for coupling Direct Simulation Monte Carlo (DSMC) and finite element method (FEM) solvers. With this approach, we can leverage existing high-fidelity solvers for both the fluid and solid domains while ensuring accurate coupling at the interface. This novel approach allows us to simulate and study a wide variety of meteoric phenomena. These include differential ablation and fragmentation, which can be predicted from the transient distribution of stresses and temperature inside the micrometeoroid. These phenomena also include shock wave and vapor cone development, which result from collisionality due to the presence of ablated meteoric material. By improving our understanding of these physical processes, our simulations provide valuable insight into the formation of radar-observable plasma signatures, enabling the correlation of radar cross section to plasma density and meteoroid mass, ultimately enhancing the interpretation of radar-based measurements.