Transient analysis of flow past sphere performing streamwise rotational oscillation using Hilbert-Huang transformation

Transients in the sphere wake have been analyzed using Hilbert-Huang transformation for different forced rotational oscillation frequencies keeping the Reynolds number and amplitude of oscillation fixed. Simulations are performed using commercial finite volume solver while the spectral analysis is done using in-house code. Time series signals of the force coefficients have been used to investigate the time dependent behavior of the wake. The effect of frequency of oscillation on growth of wake non-linearity has also been quantified. Literature indicates that forced oscillations have resonating effects on the wake and the present numerical study aims to elaborate on this aspect for the chosen problem.