Session: Flow Visualization and Regular Poster Session

Paper Number: 170532

170532 - Unsteady Wake Dynamics Behind a Sphere: A Computational and Visual Study 

Abstract: 

Understanding the flow around bluff bodies such as spheres is a fundamental problem in fluid mechanics, with wide-ranging theoretical and practical significance. This study presents a comprehensive investigation of the flow past a sphere using modern computational fluid dynamics (CFD) techniques. Flow regimes are visualized across a broad range of Reynolds numbers, revealing characteristic transitions in flow behavior. A numerical model was developed in ANSYS CFX, employing a laminar flow solver for Re < 200, and a Large Eddy Simulation (LES) approach for transitional (200 ≤ Re ≤ 3.4 × 10⁵) and turbulent (Re > 3.4 × 10⁵) regimes. LES captures large-scale turbulent structures while modeling subgrid-scale dynamics. The results indicate smooth, attached flow in the laminar regime, vortex shedding and a turbulent wake in the transitional range, and fully turbulent boundary layers with altered separation behavior in the high-Reynolds-number turbulent regime. The CFD results corroborate experimental observations by Taneda, particularly the formation of paired vortices in the wake at Re = 5 × 10⁵. CFD flow visualization techniques, including animations, further highlight the evolution of vortex structures in three dimensions, providing valuable insight into flow dynamics and enhancing understanding of unsteady wake phenomena around bluff bodies. These results are presented sequentially in a structured video with clear flow visualization.

Presenting Author: Manuel Fritsche Coburg University

Presenting Author Biography: