Numerical Simulation of Regolith Sampling Corer by Irreversible Compression Fluid Model

Abstract

The granular flow around a cylindrical corer having a forward-facing cavity on its front surface to catch the sample of the regolith layer over a celestial body was numerically analyzed using the compressible and non-expanding (CNE) fluid model. The equation of state is composed of the irreversible compression curve and the elastic unloading/recompression curves. The speed of sound for the elastic process is much higher than that in the irreversible compression, resulting in almost monotonic increase in the density through the processes. The quasi-static compression experiments by the hydraulic press for glass beads and silica sand showed that their response to the compression is appropriately described by the CNE fluid model. In the result of the one-dimensional shock tube problem with the CNE fluid model for the glass beads, the formation of the precursor wave that corresponds to the elastic process was observed in front of the shock wave that corresponds to the irreversible compression. Finally, the regolith flow around the sampling corer was numerically analyzed solving the axi-symmetric Euler equations on the moving coordinates. The characteristic features of the granular flow including the filling process of the sample were discussed.