A laboratory experiment of critical transition flow modes in Czochralski convection model was performed. The time period of temperature oscillation tp and the interval of temperature oscillation ΔT were scrutinized to capture the critical transition regime. The effects of the rotation of a model crystal rod and a model crucible were examined for three Prandtl number flows (9.10 × 102, 4.45 × 103 and 8.89 × 103). Liquid crystal flow visualization was carried out. Experiment was extended to suppress the temperature oscillation by varying the rotation rate of model crystal rod Ω = Ω0 (1 + A sin (2πft/tp)), where A denotes the rotation amplitude and f the frequency. Based on the inherent time period of oscillation tp, the oscillatory flow modes were characterized in a range of mixed convection parameter 24.3 ≤ Ra/PrRe2 ≤ 950 at Rayleigh number Ra = 4.84 × 106.

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