Instabilities in the wake of a circular disk

Area of Science:

• Fluid Dynamics
• Experimental Fluid Mechanics

Background:

• Understanding flow past bluff bodies is crucial in various engineering applications.
• Characterizing flow instabilities is key to predicting and controlling fluid behavior.

Purpose of the Study:

• To experimentally investigate the flow dynamics past a disk at intermediate Reynolds numbers.
• To determine the influence of disk aspect ratio on flow instabilities.

Main Methods:

• Utilized a low-velocity water channel for experiments.
• Employed flow visualization and particle image velocimetry (PIV) for detailed measurements.
• Tested disks with aspect ratios (χ = d/h) ranging from 1 to 24.

Main Results:

• Identified the onset and evolution of stationary and oscillatory instabilities in the Reynolds number range of 0 to 500.
• Quantified the effect of aspect ratio on instability onset and perturbation development.
• Observed distinct vorticity bifurcation branches associated with the identified instabilities.

Conclusions:

• Disk aspect ratio significantly impacts the characteristics of flow instabilities.
• The study provides valuable data on vortex dynamics and instability phenomena for disk-shaped objects.
• Findings contribute to the fundamental understanding of bluff body aerodynamics.