Modelling the flow behaviour of granular media through the dosing station of a spacecraft under low gravitational environments

The European Space Agency (ESA) will launch the EXOMARS rover mission to Mars in 2018 which will operate a rover for subsurface soil sampling and analysis. Using several electro-mechanical systems within the rover, samples acquired will be mechanically processed and dispensed to instruments. For designing the grain-processing stations of spacecraft such as EXOMARS require reliable estimates on the internal and bulk flow characteristics of granular media under low gravitational environments. However the micromechanical behaviour of granular materials under low-gravitational environments is still complex to understand. Experimental studies on the flow behaviour of grain under a low gravity, for example using parabolic flight tests to simulate Martian gravity, are difficult to perform and expensive. Using computational modelling, here we present results on the flow behaviour of granular materials through flow channels under different gravity conditions including the low-gravity regime. For this, we use three approaches, viz., (i) one-dimensional discrete layer approach (DLA) based on hybrid-Lagrange continuum approach (ii) three dimensional Kirya continuum model and (ii) three dimensional discrete element modelling (DEM). Each model has its merits and limitations. Some qualitative comparisons are also made between the flow characteristics of grains observed from parabolic flight tests and DEM simulations.