Falling jet of dry granular material in water

Modelling the flow of dry granular materials entering water is crucial for optimizing blending processes in industry and for natural hazard assessment when describing tsunami waves induced by landslides. In this study, we experimentally investigate the case of a jet of grains entering from the air into a water bath. After an initial transient state, a stationary impregnation front appears between the dry and the wet grains. The wet grains are then dispersed in the liquid. To describe this dry-to-wet transition, we focus on the first step of the process, when the liquid invades the dense granular medium. In this regime, the granular jet is modelled as a translating porous material, and we systematically characterize the impregnation process using a combination of experiments, analytical modelling, and numerical tools. We then compare this process to the situation of a confined granular jet entering a water bath. Our approach is a first step toward describing the interplay between dry grains and a liquid and the resulting dispersion of particles.