Poster Session 4, 2:15 PM - 3:00 PM: Campus Center Auditorium [A62]

Buoyancy Compensation Using Magnetic Levitation of Inertial Particles in Fluid Flows

Presenter: Milo M. Van Mooy

Faculty Sponsor: Varghese Mathai

School: UMass Amherst

Research Area: Physics

ABSTRACT

Gravity-driven flows such as surface waves, boundary-layer currents, and stratified motions govern the transport of finite-size particles in many natural and engineered environments. An increasingly relevant example is the transport of microplastic pollution in the ocean. Despite their small size, these particles have non-negligible mass which in part determines their behaviour within the waves and currents of the ocean. In order to assess health risks and find plastic removal solutions we must understand and predict where these particle aggregate and why. In general, particle trajectories reflect both gravity-related effects (buoyancy and settling) and inertia-related effects (finite response time and drag), which are coupled. This means that in practice, field observations often cannot disentangle these distinct effects. Here we develop a magnetic levitation (maglev) approach that applies an approximately constant vertical magnetic force to designed spherical particles in a water flow. The novel magnetic levitation system uses the superposition of precisely engineered coaxial permanent magnet disks, creating a  roughly 10 cubic centimeter volume within which the net buoyancy force on particles is compensated to within 10%, while horizontal forces remain below 10% of the vertical compensation. We measure the field and discuss practical limitations including tolerances and time-dependent demagnetization. This framework provides a reproducible route to buoyancy-cancellation experiments in gravity-driven flows with relevance not just to microplastics, but to numerous problems in environmental transport.

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