Visualization of flow over a golf ball at Re = 110,000

TL;DR

This study uses high-resolution Direct Numerical Simulation to analyze the flow over a golf ball at Re = 110,000, revealing how surface dimples influence flow separation and drag reduction mechanisms.

Contribution

It provides detailed DNS-based insights into the flow dynamics around a dimpled golf ball, a topic with limited prior quantitative analysis.

Findings

Flow instabilities develop near the surface.

Local shear layers cause delayed separation.

Dimples induce flow reattachment within their regions.

Abstract

The drag on a golf ball can be reduced by dimpling the surface. There have been few studies, primarily experimental, that provide quantitative information on the details of the drag reduction mechanisms. To illuminate the underlying mechanisms, Direct Numerical Simulation (DNS) is applied to the flow around a golf ball using an immersed boundary method. Computations are performed using up to 500 processors on a range of mesh resolutions from 61 million points to 1.2 billion points. Results are presented from simulations performed at a Reynolds number of Re = $1.1\times 10^5$ using a grid of 1.2 billion points. This video shows the development of instabilities in the near-surface flow, as well as the delay of complete separation due to the development of local shear layers that lead to local separation and reattachment within individual dimples.