The onset of oblique vortex shedding behind a heated circular cylinder in laminar wake regime

Oblique vortex shedding (OVS) behind a heated circular cylinder in air was experimentally investigated. Similar to that in the parallel vortex shedding (PVS), the results show that the non-dimensionalized shedding frequency, Strouhal number, decreases under the influence of cylinder heating for oblique shedding mode. Although the onset Reynolds number of OVS increases with the cylinder temperature, the onset effective Reynolds number remains 63.3 +/- 1.3 regardless of the cylinder heating. A general Strouhal-Reynolds-number relationship for OVS has been found based on the effective temperature concept in the present study. The ratio of the critical Reynolds numbers for the onsets of OVS and PVS is found to be an invariant with value of 4/3 for both isothermal and non-isothermal cases despite different length/diameter ratios and end conditions. (C) 2012 American Institute of Physics. [doi :10.1063/1.3675551]