Transition to turbulence in ferrofluids

TL;DR

This study demonstrates that ferrofluids can exhibit turbulence at significantly lower Reynolds numbers than traditional fluids, facilitated by magnetic fields, which could revolutionize turbulence research and control.

Contribution

The paper introduces the discovery that magnetic fields induce turbulence at low Reynolds numbers in ferrofluids, supported by detailed bifurcation analysis and computational ferrohydrodynamics.

Findings

Turbulence occurs at Reynolds numbers an order of magnitude lower in ferrofluids with magnetic fields.

Magnetic field strength accurately determines the onset of turbulence.

Ferrofluids enable easier experimental investigation of turbulence phenomena.

Abstract

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.