The effect of streamwise braid vortices on the particle dispersion in a plane mixing layer. II. Nonlinear particle dynamics

Abstract

A computational investigation of the nonlinear dynamics of heavy particles in a row of counterrotating strained vortices is presented. By tracking the particles numerically in the quasi-two-dimensional fluid velocity field, information is obtained on the nature of their trajectories, as well as on probability distribution functions and potential accumulation regions. The particle behavior is discussed as a function of the dimensionless strain rate, the particle Stokes number St, and the dimensionless gravity parameter Fr. Only for very low values of the St can the particles accumulate at the vortex centers. For moderate values of St, they remain trapped on closed trajectories around the vortex centers. Increasing St leads to periodic open trajectories that allow for spanwise transport of the particles. Further bifurcations lead to the generation of multiple trajectories, as well as to subharmonic solutions. Eventually, intermittent and chaotic particle dynamics are observed. In the chaotic regime, a simplified flow model is employed in order to derive various scaling laws for the particle concentration field. For strong levels of gravity, the accumulation of large numbers of particles is observed in the upwelling regions predicted in part I of the present investigation ͓B.

Parallel Algorithms for Particles–Turbulence Two-Way Interaction Direct Numerical Simulation

“…Recent reviews on the particle-demixing effects in turbulent two-phase flows can be found in [3][4][5]. Pioneering numerical simulations of tree-dimensional flows based on one-way coupling effects have been done by [1,[6][7][8][9]. However, the research on two-way momentum coupling effects in two-phase flow is still at a fundamental stage of study.…”

Streamline Topology and Dilute Particle Dynamics in a Kármán Vortex Street Flow

“…To compare with the result, we find the bifurcation process disappears when eliminate the gravity term in Eq. (8). From the above observation, we can conclude that the drag term and gravity term lead to the bifurcation behavior in dilute particle dispersion.…”

“…In a cellular flow field, aerosol particles also merge into isolated asymptotic trajectories, which are described by slow manifolds [5,6]. Moreover, the method due to the Lagrange view of particles can also be applied to investigate effects of particle dispersion on streamwise braid vortices in a plane mixing layer [7,8].…”

Dynamical Systems Approach to Particle Transport Modeling in Dilute Gas-Particle Flows with Application to a Chemical Vapor Deposition Reactor

“…In fact, this approach to the analysis of particle motion subject to a force field, which in turn depends on fields defined by a numerical simulation on some kind of discrete grid, is applicable to a wide class of dilute gas-particle flow problems. This class even includes transient flows such as particle mixing in wakes (Crowe et al, 1995) and mixing layers (see Marcu and Meiburg (1996), who also use a dynamical systems approach). Finally, it is noted that dynamical systems theory has also proven very useful in the analysis of flow patterns in single-phase fluid flows (Perry and Chong, 1987;Ottino, 1989).…”