The wake behaviour behind a heated horizontal cylinder

The behaviour of vortex structures shed from a heated cylinder is experimentally investigated by means of 2-D particle tracking velocimetry. Within this investigation the ReD number was chosen to be 73. The RiD 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 towing tank where the disturbances caused by boundary layers could be minimised. The results show that for small RiD numbers the induced heat results 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 shed from the upper half. These phenomena are assumed to be caused by a strength difference between the vortices shed from the upper half of the cylinder and the lower half. For RiD=1 the effect of the induced heat and buoyancy becomes even more pronounced resulting in a more upwards directed vortex street.