  It is known that in classical fluids turbulence typically occurs at high
Reynolds numbers. But can turbulence occur at low Reynolds numbers? Here we
investigate the transition to turbulence in the classic Taylor-Couette system
in which the rotating fluids are manufactured ferrofluids with magnetized
nanoparticles embedded in liquid carriers. We find that, in the presence of a
magnetic field turbulence can occur at Reynolds numbers that are at least one
order of magnitude smaller than those in conventional fluids. This is
established by extensive computational ferrohydrodynamics through a detailed
bifurcation analysis and characterization of behaviors of physical quantities
such as the energy, the wave number, and the angular momentum through the
bifurcations. A striking finding is that, as the magnetic field is increased,
the onset of turbulence can be determined accurately and reliably. Our results
imply that experimental investigation of turbulence can be greatly facilitated
by using ferrofluids, opening up a new avenue to probe into the fundamentals of
turbulence and the challenging problem of turbulence control.
