Wake characteristics of flow over a heated circular cylinder in the three-dimensional transitional wake regimes are studied using smoke wire flow visualizations and hot-wire anemometry techniques. The onset of wake from laminar vortex shedding to transition is found to be delayed by heating of the cylinder and the transitional wakes still developed at higher Reynolds numbers. As the cylinder is heated, vortex shedding frequencies are reduced throughout the Reynolds number range and discontinuities in St-Re relationships are typical in all temperature ratios studied. Critical Reynolds numbers for all transitional wake regimes increase linearly with increasing temperature ratios. Criteria for measuring the onset of transition for flow around a heated cylinder are proposed. Excellent agreement in Strouhal-effective Reynolds number relationships for the heated and unheated cylinders validates the applicability of the effective Reynolds number concept in both laminar and transitional wake regimes (47<Re<400).
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