Numerical investigation of a single bubble and a pair of bubbles rising in Newtonian and non Newtonian fluids with interfacial passive scalar transfer

Identifier:  TDX:4090

Handle: https://hdl.handle.net/20.500.11797/TDX4090

Authors:  Kazemi, Koorosh

Abstract:
This thesis explores the behavior of bubbles and their interaction with fluids in different industrial processes such as wastewater treatment, and chemical reactions. The study focuses on the rising dynamics of a single gas bubble and a pair of bubbles in different types of fluids, and the heat/mass transfer from the bubbles into the surrounding fluids. The simulation is carried out using Basilisk, with adaptive mesh refinement techniques. The results show that the dynamics of a single bubble are strongly influenced by the flow index and the rheological properties of the fluid. The viscosity field and bubble shape are significantly affected by the rheological properties of the fluid. The mass transfer rate increases with the Peclet number and is highly dependent on the flow index. The behavior of two bubbles rising in-line is characterized by various motion patterns. The heat/mass transfer rate is optimized in regimes where the bubbles follow side escape or Drafting-Kissing-Tumbling scenarios. The radius ratio of the leading to trailing bubble has a significant impact on the behavior of bubbles during rising. The inelastic time constant influences the behavior of bubbles during rising, leading to more instability and oscillatory motion of the bubbles. The flow index is a crucial rheological parameter that affects the behavior of bubbles, and decreasing the flow index leads to an increase in the instabilities of the bubble during rising.