Effect of Riblets Geometry on Drag Reduction


The effect of longitudinal riblet surface models (U, V and semi-Circular and U with fillet corner riblets) on the performance of unsymmetrical airfoil (NACA23015) which has been investigated numerically and experimentally. Numerical investigation involve examining drag reduction by solving the governing equations (Continuity and Navier-Stokes equations) using the known package FLUENT version (6.1) in turbulent regime with appropriate turbulence model (κ-ε). Also measurement in experimental work will be carried out. The results indicate that the riblet surface models are the key parameters for controlling the boundary layer characteristic. The most effective riblet surface is U-riblet with fillet model (Mo.4, h=0.1mm), by compare to smooth model, the results show a small increment in lift slope curve about (9%) and total drag decrease (12%) over the angles of attack range from (0° to 17°).