2D dispersion dynamics in a bidisperse granular medium under controlled curvy motions of an intruder

In a 250 mm circular frame, we investigate dispersion dynamics of 2 populations of brass hollow discs: large ones (D_ext = 6mm) and small ones (d_ext = 5mm). Mixing is performed by moving a metallic intruder inside the medium along different specific and controlled paths – particles motion is captured using a camera affixed at the bottom of the bench. Using an image processing algorithm, all particles are classified and their positions retrieved through time. With that comprehensive information, for each performed path, we explore the subsequent mixing mechanism on different levels: a macroscopic level where we focus on the overall motion of centers of mass of the two populations, a mesoscopic level where the areal concentration in large/small particles is considered and lastly a microscopic level where refined local fields such us displacement or velocity around the intruder are outlined. Other systemic parameters such as the global volume fraction or the intruder’s size are also investigated in order to assess a complete rheological picture.