Abstract
The instantaneous fluctuating velocities of particles acquired in three different flow regions of three-phase systems were measured by direct visualization. The local dynamics of particles were characterized by the deterministic chaos analysis of particle velocity fluctuations in terms of the correlation dimension obtained based on the time-delay embedding theorem. The results show that particles in the stable wake region exhibit highly chaotic velocity fluctuations with large correlation dimensions in spite of the apparently smooth trajectories with low fractal dimensions determined based on the box-counting method. In large particle systems the self-induced particle motion due to eddy shedding was found to be significant, resulting in an increase in correlation dimension with particle size. A sudden change in the correlation dimension was found to occur at the superficial gas velocity corresponding to the transition from the homogeneous bubbly flow to churn-turbulent flow regime.
