The present investigation set out to assess the influence of the surface roughness on the flow and thermal mean quantities, around the heated corrugated cylinder in the laminar steady flow. The current investigation has been devoted to a numerical analysis of a two-dimensional steady flow and forced convection heat transfer characteristics over a heated longitudinal sinusoidal shape grooved cylinder, immersed in an unconfined Newtonian fluid. The number of the grooved cavities was chosen to be 10, 20 and 30 grooves, equally distributed around the cylinder circumference with wavelength and wave amplitude of 1/50 and 1, respectively. Moreover, the thermal boundary condition effect has been analyzed by imposing a uniform heat flux and constant temperature on the cylinder periphery as a thermal boundary condition, over a Reynolds number range of ([Formula: see text]) and a fixed Prandtl number of 0.715. The numerical procedure is based on the finite volume method. The findings indicate that with increasing groove number, the total drag coefficient of the grooved cylinder reduces markedly compared to the smooth one. This trend is more pronounced as the Reynolds number increases. The effect of the groove number on the pressure coefficients is limited, where the profiles of the grooved cylinder coincide with that of the smooth one over the Reynolds number range. When the Reynolds number varies from 0.1 to 40, the average Nusselt number enhances noticeably by about 86% for the smooth and grooved cylinders. Moreover, the groove number affects significantly the average Nusselt number, where the increased groove number results in a gradual reduction in the average Nusselt number. This attenuation is more pronounced as the Reynolds number increases. To predict the average Nusselt number, a correlation has been proposed.
This paper provides the impact of roughness on the hydrodynamic behavior of the fluid over a convex-shape grooved cylinder by examining the shape and amplitude of the groove influence on the average flow rate. Direct numerical investigations of two-dimensional flow around a convex-shape grooved cylinder are performed at Reynolds number up to 100. A Reynolds number up to 40 corresponds to laminar flow in a stable state presenting the creeping and symmetry regimes and Re of 100 corresponds to laminar unstable flow presenting pure Karman vortex street flow regime. The number of grooves is set at 10, 20 and 30, uniformly spread around the periphery of the cylinder, with three different wave amplitudes of 1/50, 1/25 and 1/12.5, for each geometry. The numerical algorithm applied in this investigation is based on the finite volume method. The obtained results are compared with the smooth cylinder at the same Reynolds number, that latter shows excellent agreement with the available data in the literature. The forces acting on the cylinder are seen to be reduced by the presence of the grooves; this reduction is more significant with increasing groove amplitude, especially at a high Reynolds number. At Reynolds number equal 100, when the groove number and wave amplitude are set to 10, 1/12.5, respectively, the drag coefficient is lowered by about 10%, while the lift coefficient is reduced by around 25%.
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