Flow and heat transfer over a row of multiple semi-circular cylinders: selection of optimum number of cylinders and effects of gap ratios

The present work aims at studying the laminar flow and heat transfer characteristics of a Newtonian fluid over a row of semi-circular cylinders placed in uniform cross-flow configuration. The effects of spacing to diameter (gap) ratio, varied from 1 to 10, on the flow and heat transfer patterns have been studied at a Reynolds number of 100 for air as the working fluid. There has been no significant interaction in the flow at a spacing ratio greater than 4 and each semi-circular cylinder behaved more or less like the situation of a single cylinder. At lower gap ratios, the flow becomes more complicated due to the shear layer interactions that exist in the flow. The streamline and isotherm contours have been presented and discussed in detail for various gap ratios. The variation in flow behavior is explored further by studying the drag coefficient and lift coefficient signals of various semi-circular cylinders. The presence of a secondary frequency at low gap ratios that has adverse effect on the drag coefficient has been confirmed. The variation of measured global quantities, namely the drag coefficient, the Strouhal number and the Nusselt number have been studied and discussed in detail.