[Seminar] Hydrodynamic interaction and coalescence of rising bubbles in viscoelastic fluids: a numerical approach
Dr. Wenjun Yuan / National University of Singapore
Hydrodynamic interaction and coalescence of rising bubbles in viscoelastic fluids: a numerical approach
Understanding and controlling the interaction and potential aggregation of bubbles are of great importance to a variety of industrial and natural processes. Since the rising of a single bubble can be significantly altered by the rheology of the surrounding liquid, much attention has been devoted to the hydrodynamic interactions among bubbles in non-Newtonian fluids in recent years. In this talk, I will present our recent direct numerical simulations (DNS) on hydrodynamic interaction and coalescence of rising bubbles in a viscoelastic liquid. The numerical model has been validated by comparison with previously published results, including the terminal velocity jump discontinuity of an isolated bubble rising in a viscoelastic fluid, when its volume exceeds a certain critical value. Focusing on bubbles ascending in such a viscoelastic medium, I will mainly discuss the bubble size and number effects on the formation of a vertical chain of bubbles under different configurations. By probing the polymeric stresses and deformation, I will also address the physics behind the bubble chaining and bubble-bubble coalescence in viscoelastic fluids. My findings provide insights into the aggregation and cluster formation for bubbles dynamics in non-Newtonian fluids, as chaining of bubbles is believed to be more prevailing in highly elastic flows, in contrast to the inertia-induced dispersion.
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