Vortex tracking on visualized temperature fields in a rotating Rayleigh–Bénard convection

Abstract

We established a vortex detection method using instantaneous temperature fields that were visualized using thermochromic liquid crystals (TLCs) to investigate behaviors of vortical structures in a rotating Rayleigh–Benard convection. Experimental testing was performed at a fixed Rayleigh number $$Ra = 1.0 \times 10^7$$ and different Taylor numbers from $$Ta = 1.0 \times 10^6$$ to $$1.0 \times 10^8$$ in water containing encapsulated TLCs. Vortices were recognized as undulations that appear in the horizontal temperature fields, thus making vortex detection with high spatial resolution possible, and this enabled quantitative investigation of the dynamics of vortical structures. Standard template matching was used to detect individual vortices on visualized temperature fields, and two-dimensional curved surface fitting was adopted to remove erroneous detections and to evaluate shapes of local temperature fields corresponding to vortical structures. Additionally, vortex tracking clearly showed geometric advection pattern of vortical structures.