DOI: 10.1615/TSFP8
TURBULENT MIXING IN A PRECESSING SPHERE
RESUMO
Strong turbulence is sustained in a precessing smooth cavity. Since industrial applications of this system to mixer, chemical reaction chamber, etc. are expected, we quantify the mixing ability of sustained turbulence in a precessing sphere by the help of direct numerical simulations. More concretely, fluid particles in the sphere are numerically tracked, and the time for initially separated particles by a central plane to be mixed is evaluated. Statistics of turbulence in the sphere depend strongly on the rate of precession (the Poincare number), and therefore the mixing ability is also controlled by this parameter. When the Reynolds number defined by the spin angular velocity, the radius of sphere and the kinematic viscosity of fluid is fixed at Re = 40000, the most efficient mixing is achieved when Poincare number is about 0.07.