FSU Mathematics
Mathematics Colloquium
Daniel M. Harris
Brown University
Title: Hydrodynamic
mechanisms for particle aggregation at fluid interfaces
Date: February 14th, 2020
Place and Time: Room 101, Love Building, 3:35-4:25 pm
Refreshments: Room 204, Love Building, 3:00 pm
Abstract.
Understanding the forces on small bodies at fluid interfaces has
significant relevance to a range of natural and artificial systems. In this talk, I will discuss two recent
investigations of fluid-mediated attraction mechanisms of non-Brownian
particles, at free surfaces and within density stratified fluids.
In the first part, I will present direct measurements of the
attractive force between centimetric disks floating at an air-water
interface. It is well known that objects
at a fluid interface may interact due to the mutual deformation they induce on
the free surface, however few direct measurements of
such forces have been reported. In the present work, we characterize how the
attraction force depends on the disk radius, mass, and relative spacing. The
measured forces are rationalized with scaling arguments and compared directly
to numerical predictions.
In the second part, I will describe a novel attractive mechanism
by which particles at isopycnals within a density
stratified fluid may self-assemble and form large aggregates without need for
short-range binding effects (adhesion).
This phenomenon arises through a subtle interplay of effects involving
solute diffusion, impermeable boundaries, and the geometry of the
aggregate. Control experiments with two
particles isolate the individual dynamics, which are quantitatively predicted
through numerical integration of the underlying equations of motion.
Ongoing and future work in these areas will also be
discussed.