Herman Clercx
Phys. Dep. Eindhoven University of Technology, Eindhoven, The Neatherlands

Lagrangian analysis of turbulent rotating convection

This study focuses on exploring how the flow transition from one state to the other in rotating convection will affect the Lagrangian statistics of (fluid) particles. Up to now, the global parameters like the overall heat transfer or the wind Reynolds number are used to characterize the different turbulent states. However, it is obvious that the flow transition from weakly rotating Rayleigh-Benard (RB), with the large-scale wind still present, to strongly rotating turbulent RB convection characterized by vertically-aligned columnar vortices is also reflected in the Lagrangian dynamics of immersed tracer particles. We have employed 3D Particle Tracking Velocimetry (3D-PTV) in a water-filled cylindrical tank of equal height and diameter 200 mm. The measurements are performed in the central volume of 50 x 50 x 50 mm^3 at a Rayleigh number Ra = 1.28e9 and Prandtl number Pr = 6.7, and near the top plate. We are reporting the velocity and acceleration pdfs for different Rossby numbers in the centre of the domain and near the top plate and how transition from weakly rotating RB to strongly rotating RB affects the acceleration and velocity pdfs. Additionally, we will briefly discuss the velocity and acceleration autocorrelation functions.