Vehicle Aerodynamics: Drag Reduction by Surface Dimples

For a bluff body, dimples behave like roughness
elements in stimulating a turbulent boundary layer, leading to delayed
flow separation, a smaller wake and lower form drag. This is very
different in principle from the application of dimples to streamlined
body, where any reduction in drag would be predominantly due to a
reduction in skin friction. In the present work, a car model with
different dimple geometry is simulated using k-ε turbulence modeling
to determine its effect to the aerodynamics performance. Overall, the
results show that the application of dimples manages to reduce the
drag coefficient of the car model.

• C. K. Chear
• S. S. Dol

• Aerodynamics
• Boundary Layer
• Dimple
• Drag
• Kinetic Energy
• Turbulence.

[1] Ahmed, S.R., Ramm, G. & Faltin G. (1984). Some salient features of the
times-averaged ground vehicle wake. SAE Society of Automotive Eng.,
Inc, 1(840300):1 – 31.
[2] Dol, S.S., Kopp, G.A. & Martinuzzi, R.J.M. (2008). The suppression of
periodic vortex shedding from arotating circular cylinder. Journal of
Wind Engineering and Industrial Aerodynamics 96, 1164 – 1184.
[3] Hermann, L., Michael, B. & Cagatay, K. (2008). Drag Reduction by
dimples? A Complementary Experimental/Numerical Investigation.
International Journal of Heat and Fluid Flow 29(3), 783 - 791.
[4] Munson, B.R, Young, D.F. & Okiishi, T.H. (2002). Fundamentals of
Fluid Mechanics, 4th Edition, John Wiley and Sons.
[5] Srivastav, D. (2012) Flow control over airfoils using different shaped
dimples. International Conference on Fluid Dynamics and
Thermodynamics Technologies (p. 92-97). Singapore: IACSIT Press.
[6] White, F.M. (2003). Fluid Mechanics, 5th Edition McGraw Hill.