Computational and Experimental Studies of Characteristics of the Flow Drag, through Dimpled Square Cylinders

Drag forces on hemispheric dimples in parallel and zigzag configuration on square cylindrical arethe focus of investigation and analysis in this paper. The research method has been carried out with a computer fluid dynamic (CFD) program using ANSYS FLUENT 18.0. The test piece has been made of acrylic in a total of 9 pieces with length of 300 mm, width 100 mm and height of 100 mm and dimpled ratio DR = 0.5. Dimples are arranged in rows, numbered from 1 to 8. All the specimens are treated in 7 equal flow velocity rates, ranging from 8 m/s to 20 m/s. The study which took place in laminar flow region with Reynolds number (Re) of 50064 to 125161 indicates that, the use of hemispherical dimples in both parallel and zigzag configurations reduces the drag coefficient (Cd ). For example,in the same Re = 125161 the value of Cdon the plate without dimples was of 1.272, while on square cylinders with dimples in parallel configuration, the smallest drag coefficient, obtained on 2rows was of 1.203, and on dimpled square cylinder with zigzag configuration the smallest Cd was of 1.216, which was also on 2-rows configuration. Moreover, when compared with the square cylinder without dimples, the percentage of reduction drag coefficients are 4.396% and 5.412% for dimpled square cylinders in zigzag configuration and parallel configuration, respectively. The results show that the use of parallel configuration gives higher reduction than zigzag configuration.