State U., Mathematics
Ferrofluids are dilute colloidal suspensions of magnetic nanoparticles in a carrier
liquid. Because they are easily manipulated with modest magnetic fields, ferrofluids
are in use in a wide range of applications. Continuum descriptions of their behavior
are complicated by the presense of asymmetric stresses and the need for phenomenological
models of the magnetization. In this talk I will describe recent work at Montclair
State University in two areas. The first: ferrofluid shear in a microchannel, employs
asymptotic models to examine the possibilities for magnetic flow pumping. The results
also highlight the relevance of the boundary condition for internal angular momentum
in continuum descriptions of structured continuua.
The second problem is that of bubbles in ferrofluids. Here I will describe numerical
solutions for the shapes of stationary and rising bubbles, examine the companion
problem of ferrofluid droplets, and discuss the development and validation of code for direct
numerical simulations of interfacial ferrofluid problems. I will conclude by describing
experiments recently begun by collaborators at Argonne National Labs to visualize
bubbles rising in ferrofluids using a new technique.