Confined Flow over Semi-circular Cylinder in Steady Flow Regime

Abstract

The detailed flow and thermal fields have been presented for the steady mixed convection heat transfer from a semi-circular cylinder placed in a rectangular channel. The semi-circular cylinder is symmetrically placed in a rectangular channel in such a manner as curved surface of the semi-circular cylinder is facing the upward oncoming flow and gravity is acting in downward direction (‘-’ve y-direction). Hence, the buoyancy is also directed in the same direction. This study spans the following ranges of conditions 1≤Re≤50; 0.7≤Pr≤50; 0≤Pr≤2 and Confinement ratio (β) = 4. The numerical predictions are analyzed in terms of the distribution of pressure coefficients, drag coefficients, local and averaged Nusselt numbers over the aforementioned ranges of the influencing parameters. The streamline patterns show that the wake is being suppressed under confinement and isotherms are get clustered around semi-circular cylinder. At low Reynolds number, the maximum value of pressure coefficient found at front stagnation point followed by sudden drop at sharp corners whereas at high value of Reynolds number, the drop in the value of pressure coefficient at corners are relatively small than low Reynolds number. The maximum value of the local Nusselt number is found at front stagnation point. At the sharp corners, the local Nusselt number suddenly decreases and small recovery is seen at rear flat surface. As expected, the drag coefficient decreases with increases in the value of Reynolds number whereas the average value of Nusselt number increases with gradual increase in the value of Reynolds and Prandtl number. The Richardson number shows complex influence on the flow and heat transfer characteristics.