Session: Flow Visualization and Regular Poster Session

Paper Number: 170536

170536 - Experimental Flow Visualization Around a Sphere Using Particle Image Velocimetry 

Abstract: 

Understanding the flow around bluff bodies such as spheres is a classical and widely studied problem in fluid dynamics, owing to its theoretical complexity and relevance in many engineering applications, including aerodynamics, environmental flows, and process engineering. This study investigates the evolution of flow structures around a sphere across a wide range of Reynolds numbers using Particle Image Velocimetry (PIV), a non-intrusive, high-resolution optical measurement technique. The flow is categorized into three distinct regimes: laminar (Re < 200), transitional (200 ≤ Re ≤ 3.4 × 10⁵), and turbulent (Re > 3.4 × 10⁵). In the laminar regime, flow remains symmetric with a steady wake structure. As the Reynolds number increases, the flow enters a transitional phase characterized by periodic vortex shedding, asymmetric wake patterns, and increasing instability. In the turbulent regime, both the boundary layer and wake become highly disordered, exhibiting early flow separation and complex turbulent structures. Flow visualization reveals features consistent with historical experimental observations by Taneda, including the appearance of paired vortices behind the sphere at high Reynolds numbers. Time-resolved PIV measurements provide detailed insight into instantaneous velocity fields and vortex evolution, enhancing our understanding of unsteady wake dynamics. The results underscore the importance of experimental flow visualization techniques in validating theoretical models and capturing real-world fluid behavior.

Presenting Author: Ivana Milanovic University of Hartford

Presenting Author Biography: