The wake behaviour behind a heated horizontal cylinder

The behaviour of vortex structures shed from a heated cylinder is experimen tally investigated by means of 2-D particle tracking velocimetry. Within th is investigation the Reo number was chosen to be 73. The Ri(D) number, the dimensionless number which presents the relative importance of the induced heat, varies between 0 and 1. The experiments were carried out in a large t owing tank where the disturbances caused by boundary layers could be minimi sed. The results show that for small Ri(D), numbers the induced heat result s in a deflection of the vortex street in negative y-direction. Within the vortex street a linking of two subsequently shed vortices occurs where the vortex shed from the lower half of the cylinder rotates around the vortex s hed from the upper half. These phenomena are assumed to be caused by a stre ngth difference between the vortices shed from the upper half of the cylind er and the lower half. For Ri(D) = 1 the effect of the induced heat and buo yancy becomes even more pronounced resulting in a more upwards directed vor tex street. (C) 1999 Elsevier Science Inc. All rights reserved.