Flows past a tiny circular cylinder at high temperature ratios and slight compressible effects on the vortex shedding

Kurzfassung

The present study contributes to the numerical simulations of weak compressible effects for laminar flows around heated circular cylinders. Our aim in this work is to understand the physics of the flow around a heated cylinder and the reasons for the decrease in the frequency of vortex shedding in the wake behind the cylinder as the ratio of surface temperature to freestream temperature increases for moderate Re numbers. The previous achievements on this subject rely mainly on experimental investigations by using a "representative" or "film temperature" and therefore should be investigated more accurately by the numerical considerations. In that context, numerical experiments are carried out. A technique which was previously tested and validated on a variety of flow problems is utilized in the numerical experiments. The results show that the temperature is not a passive contaminant especially for flows with temperature ratios greater than 1.1. The temperature boundary layer surrounding the wall introduces weak compressible effects on the velocity and on the pressure field especially for Re numbers below 100. As a consequence of this result, the local Ma number effects are shown on a Re-Nu curve for the laminar unsteady vortex shedding regime.