Effect of external pulsation on kinematics of fluid particles in the field of Lamb–Oseen vortex pair

Abstract

The effect of external pulsation on a pair of stationary Lamb-Oseen vortices of equal strength has been analyzed to investigate kinematic behavior of a fluid particle. The assumption of vortices being treated stationary or fixed vortex filaments is valid in a reference frame attached to the vortex system with axes along and perpendicular to the line of their centers. Also, it is assumed that change in core shape and size is much small, with least possibility of core merger. In such situations, periodic particle paths are observed and superposition of pulsation becomes beneficial. In the present work, motion of a representative fluid particle is modeled as a non-linear dynamical system by varying both amplitude and frequency of external pulsation. Effect of external pulsation has been brought out with the help of quantification of deviation from periodic paths by using the concept of total average deviation. Results are presented in terms of particle paths, velocity phase plots, velocity signals and their spectra for varying amplitude and frequency of external pulsation.

Effect of Pulsation in Relative Vortex Strength on the Evolution of A Material Line In A Pair Of Viscous Vortices

“…In the case of Lamb-Oseen vortices, there is a Gaussian distribution of vorticity with maximum vorticity at the centre of the vortex. The basic non-dimensional formulation of governing equations is derived by Pai et al [10] and is given by…”