The convective flows on a heated horizontal plate are studied by experiments using background-oriented schlieren and three-dimensional particle tracking velocimetry methods. The transient flow structures and a series of transitional flow states are found as the Rayleigh number increases at Pr = 7. The scaling laws of the starting plume are verified with experimental results. In the fully developed state, experimental data show that when the Rayleigh number is less than 3.54 × 105, the flow exhibits an axisymmetric quasi-constant state; with the increase in the Rayleigh number, the plume becomes a periodic flapping state and finally enters a chaotic state. Dynamic mode decomposition is also used to analyze the flow characteristics. Moreover, the velocity and flow rate of the transitional flow from the experimental data are compared with numerical results and scaling laws obtained in previous studies and show good agreement.
Jiang et al. (Sun,) studied this question.