CFD-DEM simulation of lunar regolith particle motion during spacecraft landing using a supersonic multiphase solver
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Space agencies like NASA and ESA have the aim to send the human back to the Moon. However, the establishment of infrastructure on the lunar surface renders it imperative to minimise dust emissions caused by spacecraft exhaust gases. Consequently, the utilisation of an in-situ manufactured lunar landing structure is planned to avoid dust emissions. In light of the extreme conditions, which include reduced gravity, high vacuum and sharp particle morphology, a combination of experiments and simulations is utilised to elucidate the interaction between the lunar landing platform, the regolith particles and the lunar environment. The simulation is performed utilising a combination of computational fluid dynamics (CFD), direct simulation Monte Carlo (DSMC) and discrete element method (DEM) [1, 2]. The present study is dedicated to the simulation of the trajectories of particles stirred up during the landing of a spacecraft (Figure 1), and the necessary adjustments to the numerical simulation. For this purpose, a compressible CFD-DEM solver based on the PIMPLE algorithm (a combination of the PISO and SIMPLE algorithms) was developed. The solver was adapted, verified and validated in such a way that it can resolve flows at speeds in excess of ten times the speed of sound. In order to achieve this objective, the pressure equation was modified in such a manner that it could accommodate the hyperbolic nature of supersonic flow. Additionally, a force model based on the drag model of Loth et al. [3] was implemented that considers the correlation between the drag force values acting on the particles and the Mach and Reynolds number.
