Study of flow over dimpled cylinder

• Main Author: Tan, Shu Pei
• Other Authors: Ng Yin Kwee
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Mechanical engineering::Fluid mechanics; DRNTU::Engineering::Aeronautical engineering::Aerodynamics
• Online Access: http://hdl.handle.net/10356/61350
• Institution: Nanyang Technological University

Drag reduction of flow over a circular cylinder is done through by having a dimpled surface. Computational fluid dynamics (CFD) simulations are done to investigate the degree of drag reduction by dimpled cylinder as compared to smooth cylinder and the results are to be validated by wind tunnel experimentations. The simulations were conducted for Reynolds number (Re) ranging from 20,000 to 160,000 which correspond to the critical Re range of a golf ball. The aerodynamics coefficients such as drag coefficient and pressure coefficient were compared between both cylinders and the results had shown effective drag reduction by an average of 9.16%. On the other hand, experimentations were carried out for Re 60,000 to 140,000 due to wind speed limitations and the differences were significant as compared to the simulation results. These were mainly due to the interference of flow during the experiment and the inaccuracies of the CFD model. Pressure drag for both experiment and simulations was calculated using pressure coefficients and the results showed good agreement. Optimisation of dimple parameters was also done and the optimised dimple depth is 0.5mm and dimple diameter is 7mm.