“…The research presented in this paper addresses multi-material flow situations encountered in geomechanics and geotechnical engineering. Examples are natural hazards like landslides [18,19], avalanches and debris flows [20,21,22], liquefaction-induced soil failure [23,24], and elementary installation processes like digging, injection, mixing, displacement, or penetration [25,26,27,28,29]. Schematic views are shown in Fig.…”