Thermo-fluids effects of a grooved circular cylinder in laminar flow regimes

Abstract The force coefficients and heat transfer related to a circular cylinder with grooved surfaces are studied at Re ≤ 200. Three types of grooved surfaces are examined: square, triangle, and dimple. The grooves are arranged at θ = 0°, 30°, 45°, 60°, 90° from the forward stagnation point of the cylinder. It is shown that the existence of a groove controls the dynamic behavior of the vortices; as such lift and drag coefficients have been varied considerably, depending on the shape of the groove and θ. The coefficients appear very sensitive to triangle grooved surface, in particular, as θ varies to 45°. The results reveal that triangle grooved surface could produce minimum drag coefficient when θ varies to 450 for all examined Re; this is found much lower than that of the square and dimple grooved surfaces and even smooth cylinder. A significant enhancement of the Nu is attained in the wake of the triangle grooved cylinder surface with the angle of the location of 450. At low Reynolds number (Re = 50), the Nu value of triangle grooved surface with θ = 0°is shown higher than that of other grooved surfaces, whereas this value is found to the lowest at high Reynolds number (Re = 200).