Non-Newtonian Fluid Mechanics: ENVR 400 In-house Seminar

Chris Bowers, doctoral student in the Department of Environmental Sciences and Engineering, will present this week’s seminar in the department’s Spring 2019 series. Bowers’s talk is titled, “Where does it go? Non-Newtonian fluid mechanics in hydraulic fracturing systems.”

Abstract

Over the last 20 years hydraulic fracturing, more commonly fracking, has become a hot button issue to policy makers, scientists, and average citizens due to its potential impact on economical energy production, reduction of greenhouse gases compared to coal combustion, and potential, largely unknown environmental impacts. Hydraulic fracturing systems are vast, with one well impacting a radius a few miles wide. Additionally, the common use of non-Newtonian fluids increases the complexity of the situation. Non-Newtonian fluid mechanics has been rarely studied in the context of porous media systems in the past, which has led to a gap between industrial  application and understanding of the fate and transport of hydraulic fracturing fluids. To elucidate what is occurring during hydraulic fracturing operations, a combination of experimentation, computational modeling, and theory was used to progress the scientific understanding of non-Newtonian fluid mechanics. Experiments were conducted using packed columns of sand and guar gum, a non-Newtonian fluid which is commonly used in hydraulic fracturing, to determine how the fluid rheology impacts the hydraulic conductivity of packed media. Radioactive tracer tests were also done to view similar effects on the dispersivity of media. These macroscale results were compared to microscale simulations, which used a combination of lattice Boltzmann modeling and OpenFOAM, an open-source fluid modeling toolkit. These models are used in conjunction with the Thermodynamically Constrained Averaging Theory (TCAT) to develop an understanding of the underlying processes that are impacting macroscopic flow behavior. TCAT has been used to derive an averaged macroscopic formulation of hydraulic conductivity for systems with non-Newtonian flow. These results have led to new understanding of how non-Newtonian fluid behavior impacts hydraulic fracturing systems.

Please contact Dr. Howard Weinberg, howard_weinberg@unc.edu, if you have any questions.