Particle tracking of inertial and Lagrangian particles in isotropic turbulence flows

Kurzfassung

The motion of contracting and expanding bubbles in an incompressible chaotic flow is analyzed in terms of the Finite-Time Lyapunov Exponents. The viscous forces acting on the bubble surface depend not only on the relative acceleration but also on the time-dependence of the bubble volume which is modeled by the Rayleigh-Plesset equation. The effect of bubbles coalescence on the coherent structmes that develop in the flow is studied using a simplified bubble merger model. Contraction and expansion of the bubbles is favored in the vicinity of the coherent structures. Mixing patterns were found to depend heavily on merging and on the time-dependent volume of the bubbles.