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Simulation of magnetic positive positioning of propellants (MP 3 ) in full-scale applications depends on the ability to model the shape and strength of the magnetic fields required to induce fluid flow. A previous effort to integrate an electromagnetic field and incompressible fluid flow model yielded a unique tool that can be used to predict fluid motion induced by a magnetic field. The enhanced computational simulation is used to predict an optimal configuration for an upcoming flight experiment focused on studying the influence of a magnetic field on LOX in reduced gravity. Simulations of magnetic positive positioning of LOX are presented and the influence of the magnetic field and background acceleration on the settling time is investigated to determine an appropriate tank and liquid configuration to induce successful reorientation during the flight experiment. Variations in the magnet thickness, LOX tank size, background acceleration, and LOX tank fill are considered to predict the optimal experiment design. The magnetic Bond number and a dimensionless reorientation time are utilized as correlating parameters for this study and may be useful in future efforts to relate magnetically induced flows for small-scale experiments to the behavior of propellants in full-size systems.

International audience; Suffusion refers to a special form of internal erosion characterized by the selective erosion of the finest particles of a soil under the action of an internal fluid flow. In this work, the microscopic mechanism of particle detachment in binary mixtures subjected to suffusion under different flow directions is analyzed. We use the coupled lattice Boltzmann method (LBM) and discrete element method (DEM) to simulate the suffusion process in a granular sample subjected to an anisotropic stress state. When the macro flow direction is aligned with the principal direction of compression, it is found that the fluid flow is more intense, which increases erosion. The stress anisotropy also influences the detachment direction that is not necessarily correlated with the macroscopic flow direction. The sample's anisotropic stress state is responsible for directional variations in microstructural properties during the suffusion under different flow directions. From a micro scale point of view, a contact sliding index P and a particle detachment index Δ are defined to demonstrate that fluid-induced sliding dominates for particles about to detach.