Modeling ferrofluids for fun and profit

Philip Yecko

Montclair
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.