  We investigate the enhancement of both mixing and heat transfer in a two-rod
mixer for highly-viscous non-Newtonian fluids. The mixer is composed of two
vertical, circular rods in a cylindrical tank. Chaotic flows are obtained by
imposing the temporal modulations of the rotational velocities of the walls. We
study the effects of different stirring protocols, which lead to non-chaotic
and chaotic flows, on the efficiency of both mixing and heat transfer for three
different rheological fluid behaviors: shear-thinning, Newtonian and
shear-thickening. For this purpose, we use statistical indicators that
characterize the mean value of the fluid temperature and its homogenization. We
find that chaotic mixing is suitable for shear-thickening fluids for which we
observe a clear enhancement of the thermal mixing (heat extraction and
homogenization). This is due to the increase in the apparent fluid viscosity in
the vicinity of the rotating walls. This aspect confirms the relevance of
chaotic mixing for highly-viscous fluids.
