2024 AIChE Annual Meeting
(522b) Granular-like Behavior of Dense Microroller Systems
Authors
Gilchrist, J. - Presenter, Lehigh University
Wilson-Whitford, S., Lehigh University
Roffin, M. C., Lehigh University
Gao, J., Lehigh University
Sisca, M., Lehigh University
Granular matter flows, fluidizes, segregates, and generally behaves as a non-Newtonian fluid in its dense flow regime. This work investigates the granular-like behavior of dense systems of microrollers that are responding to rotating magnetic fields. Microrollers also flow, segregate, and fluidize with kinematics similar to those found in granular systems. In this work, a granular system of 50 micron ferromagnetic Janus particles is prepared. These responsive Janus particles are rotated through the application of magnetic torque by an external rotating magnetic field resulting in uphill granular heaping which for all purposes demonstrates quintessential granular behavior, such as boundary layer flow, but against gravity, giving rise to a negative angle of repose (downhill to uphill). It is proposed that the behavior is governed by frictional control as a direct result of the magnetic field strength. Flow through funnels, up stairs, through porous media, and mixing and segregating with non-responsive particles will be demonstrated. These observations elucidate a new way to observe granular systems and have a significant impact on the way in which granular systems could be applied.