Investigation of flow around a spinning ball

• Main Author: Muhammad Hanif Mustadza
• Other Authors: Chan Weng Kong
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Mechanical engineering::Fluid mechanics
• Online Access: https://hdl.handle.net/10356/150665
• Institution: Nanyang Technological University

An investigation of the aerodynamic forces involved in sports balls was carried out. This project used a CFD software, ANSYS Fluent, to carry out the simulation of a sphere rotating in an airflow. The simulation consisted of 3 important stages: geometry, meshing and set-up. The geometry was set up to simulate a sports ball rotating in an airflow using information obtained from the literature review. A mesh of sufficient quality was generated to ensure accurate simulation of flowlines around the sphere. The initial and boundary conditions for every case was then keyed in during the set-up phase. A total of 40 different case simulations were carried out. The results obtained showed that a greater rotational velocity, will result in a greater lift coefficient, Cl, mainly due to the difference in air stream deflection. The results also showed that a greater free stream velocity, U, will delay the separation of the boundary layer and will results in less downward deflection of the airstream, causing Cl to decrease. As for the drag analysis, as rotational velocity increases, a larger wake region will form behind the sphere, thus increasing the amount of pressure drag on the sphere. As U decreases, a larger wake region is formed behind the sphere and thus, the sphere experiences more pressure drag. Therefore, the results showed that drag coefficient, Cd, increases as rotational velocity and U increases and decreases, respectively. Although a smooth and solid sphere was used in the simulation, future works can be done to replicate the geometry of a football or any other sports ball more accurately. A more realistic geometry could result in significantly different results.