Investigation of granular impact using positron emission particle tracking

• Impact of dense spheres onto fluidized beds results in a jet.
• Sphere trajectory tracked using PEPT.
• Individual particle motion in the bed tracked with PEPT.
• Simultaneous tracking shows potential for PEPT in granular impact phenomena.

We present results from an experimental study of granular impact using a combination of high-speed video and positron emission particle tracking (PEPT). The PEPT technique exploits the annihilation of photons from positron decay to determine the position of tracer particles either inside a small granular bed or attached to the object which impacts the bed. We use dense spheres as impactors and the granular beds are comprised of glass beads which are fluidised to achieve a range of different initial packing states. For the first time, we have simultaneously investigated both the trajectory of the sphere, the motion of particles in a 3-D granular bed and particles which jump into the resultant jet, which arises from the collapse of the cavity formed by the impacting sphere.

Figure optionsDownload as PowerPoint slide