Study of flow over dimpled cylinder

• Main Author: Lim, Meng Hee.
• Other Authors: Ng Yin Kwee
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Mechanical engineering
• Online Access: http://hdl.handle.net/10356/54006
• Institution: Nanyang Technological University

Fluid flow around a circular cylinder is controlled by dimpling the surface of the cylinder to reduce drag forces acting on it. Numerical simulation and wind tunnel experimentation on the flow around a smooth and dimpled cylinder are carried out to investigate the effectiveness of dimples on drag reduction. Numerical simulations were conducted over a Reynolds number range of 20,000 to 160,000, which was similar to the critical Reynolds number range of golf balls. Drag coefficient values were compared between the two different cylinders and simulation results had shown that the dimpled cylinder had a lower drag coefficient than the smooth cylinder over a Reynolds number range of 20,000 to 75,000. For the Reynolds number range of 75,000 to 160,000, the drag coefficient of the dimpled cylinder was slightly higher than the smooth cylinder by an average of 4%. In order to validate the simulation results, wind tunnel experiments were conducted. Wind tunnel experiments were conducted over a Reynolds number range of 60,000 to 140,000 due to wind speed limitations. Experimental results showed that the dimpled cylinder was able to reduce the drag coefficient by an average of 12%. It is evident that these findings will help in future developments in the aspects of dimpled cylinder design, testing and further research.