Figure 1
APS/Carin Cain

Figure 1: Researchers have explored properties of turbulence in two important situations: (Left) A layer of fluid of thickness d under the influence of gravity g is heated from below, so that the temperature Tb is higher than the temperature Tt at the top (Rayleigh-Bénard case). When the temperature difference is sufficiently large, a transition from the state of pure heat conduction to a state of convection occurs. He et al.’s experiment [1] focuses on the asymptotic state of highly turbulent convection. (Right) In a Taylor-Couette system, a fluid fills the gap between coaxial cylinders with radii ri and ro, d=ro-ri, which rotate independently with the angular velocities Ωi and Ωo, respectively. At high enough rotation differential, Ωio>0, a transition from the purely cylindrical flow to axially symmetric Taylor vortices occurs. The latter become turbulent at much higher values of Ωio, which is the regime investigated in Huisman et al.’s experiment [2].