Spheres Settling in Stratified Fluid: Experiment Versus Theory (2016)

Undergraduates: Gabriella Stein, Claudia Falcon

Faculty Advisor: Roberto Camassa
Department: Undecided

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Particles falling through stratified density layers of fluids occur throughout the natural world and affect various aspects of life such as the formation of thin layers of marine aggregates in the ocean, pollution clearing tides, and air quality. The experimental setup consists of a sphere falling through two layers of stably, sharply stratified corn syrup with matched viscosities. The top layer sits above the denser bottom layer and a sphere of higher density that both layers is dropped in this configuration. In this study, we sequentially change the bottom layer density to approach the density of the sphere, the experiment is filmed and the data is analyzed, which allows us to track the sphere¿s position and velocity profiles. There are many difficulties when running these experiments including stratifying the layers sharply by diluting salts, matching the viscosities of the layers, as well as suppressing convection. These sets of experiments helps us understand the validity of the theory currently published by determining if salt diffusion plays a role in a new regime where the sphere exhibits prolonged residence time at the interface.