59th Annual Report on Research 2014

The objective of this project is to research the effects of interface-bound particle presence on the contact dynamics of bubbles in confining flow conduits, aiming to demonstrate particle-coated bubbles as a potential technology for preventing flow blockage during petroleum recovery. In particular, the focus is on how incorporating the bubble surface with electric charges prevents droplet contact with the conduit walls.

During the first year of this ACS PRF award, research progress has been made in several fronts. First, we began developing our fluorescence microscopy capabilities for quantifying the thin film thickness over time. To achieve this, fluorescent dyes were dissolved into a liquid solution that serves as the continuous phase, while the bubbles were left as dye-free. Ongoing work includes correlating the fluorescence intensity with the thickness of the thin film that separates the bubble from the flow channel wall during bubble deformation. Second, we developed new thin-film evolution equations that better model the force interactions between bubble surface tension, electrostatic and van der Waals interactions between the bubble, the flow channel wall, and the surface-coating particles. We are currently taking numerical approaches to evaluate these nonlinear partial differential equations. The measured thin film thickness from experiments will be used as initial conditions for solving these evolution equations. Finally, we have chosen to add a numerical modeling approach to study bubble deformation and thin film drainage in confining conduit walls. The numerical modeling investigation complements the experimental measurements and the theoretical analysis and will help us better understand the fundamental physical interactions. Commercial software package COMSOL Multiphysics, which uses the Finite Element and Moving Mesh methods to solve for electrostatic, ion transport, and fluid dynamic interactions simultaneously, was adopted to model clean and surface-charged droplet deformation and thin film drainage. Our results show that when the bubble surface and the conduit wall become likely charged, the electrostatic repulsion provides a countering force against the bubble surface tension and slows down the thin film drainage and bubble deformation. In addition, this effect becomes observable even at thin film thickness much larger than the electric double layer’s Debye length. Upcoming research in modeling includes finding the equilibrium thin film thickness for charged bubble surface, and incorporating charged solid particles onto the bubble surface.

In addition, the ACS PRF award has brought research and education impact to the principal investigator (PI) and his graduate students at Binghamton University. True to the spirit of the New Direction grant, this award has allowed the PI to begin a new research thrust in multiphase flow, interfacial phenomena, and a petroleum-relevant technology. In addition, the PI was able to branch out from being an experimentalist and venture into multiphysics computational modeling in predicting complex fluid phenomena.

The ACS PRF award has so far supported two graduate students in their research and educational careers. Dr. Wei Wang graduated with his PhD degree in May 2014 with the support of this award, and laid the foundation for the experimental work of this project. Mr. Jonathan Hui is completing his Master’s Thesis on computationally modeling charged droplet deformation and thin film drainage in a confining conduit, and will continue to pursue a PhD degree under the guidance of the PI, focusing his research effort in computationally modeling and experimentally quantifying particle-coated bubble interactions confining channel walls. The PI and his graduate students presented their preliminary findings at the 67^th American Physical Society Division of Fluid Dynamics conference held in Pittsburgh, PA.