  The falling of an object through a non-Newtonian fluid is an interesting
problem, depending on the details of the rheology of the fluid. In this paper
we report on the settling of spherical objects through two non-Newtonian
fluids: Laponite and hair Gel. A falling object's behavior in passing through a
thixotropic colloidal suspension of synthetic clay, Laponite, has been reported
to have many behavioral regimes. Here we report observation of a new regime
where irregular motion is observed. We argue that this irregular motion may be
interpreted as onset of chaos. Observation of this regime depends on the size
of the falling sphere, relaxation time of fluid and concentration of particles
in the suspension. Similar experiments in Gel, a yield stress polymeric fluid,
do not reveal such behavior.
