CFD–DEM simulation and experimental investigation of the flow behavior of lunar regolith JSC-1A

Abstract

Rovers on Mars and the Moon analyze the local geology by collecting samples of the upper layer in containers and ovens. After the analysis, the complete discharge of samples from the reservoir must be ensured. Because of the low atmospheric pressure, reduced gravity, and different grain shapes of the bulk material, the discharge process is very different compared to that on Earth. In this study, the behavior of lunar regolith JSC-1A in closed containers during discharge was investigated by analyzing the flow in an hourglass under the Earth’s atmosphere. Reproducible fluidization of the top particle layer was observed during the outflow of the upper half of the hourglass. These particles were fluidized by the displacement flow initiated by falling particles in the completely closed container. This complex problem was simulated by coupling computational fluid dynamics (CFD) with the discrete element method (DEM). A CFD–DEM simulation with 1million particles was performed. Because billions of particles are present in the actual system, the use of a coarse graining approach was required. In addition, high-speed camera measurements were used to determine the velocities of individual particles to validate the simulation. The fluidization effect was successfully simulated using the coupled method.