Collaborative Research: Hydrodynamic mechanisms for flow-induced self-assembly in confined complex fluids

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CBET - 1603627; 1603806PIs: Blawzdziewicz, Jerzy; Loewenberg, MichaelThe goal of this collaborative project is to explain an interesting phenomenon that is observed when liquid droplets in an immiscible liquid flow in confined spaces. For certain conditions, the droplets line up to form chains of drops that persist and sometimes coalesce to form thin liquid strands. Chain formation is only observed for confined emulsions of deformable drops. The investigators hypothesize that small changes in the flow, caused by the deformable drops, induce the drops to align in chains. The hypothesis will be tested by carrying out numerical simulations that solve the equations governing the deformation of the drops and their motion in confined flows. By varying material parameters, the investigators can gradually increase the extent of drop deformation, which should be correlated with the degree of chain formation. The research team will collaborate with a researcher at the National Institute of Standards and Technology who first observed the chaining phenomenon experimentally. Additional experiments will be carried out to compare data with the computer simulations developed in this project. The team expects that understanding the microscale flow patterns leading to drop alignment can be harnessed to make new microstructured materials. The researchers will engage local high school students in Yale's Pathway to Science Program by teaching students to write simple computer programs that simulate motions of particles in fluids. They will also develop activities for fifth through eleventh grade girls attending a residential summer camp at Texas Tech called "Science: It's a Girl Thing."The project will verify the hypothesis that quadrupolar flow-field patterns produced by deformable immiscible drops in a strongly confined shear flow are responsible for the formation of ordered structures in confined emulsions. A hierarchy of many-particle, computer simulation algorithms will be developed to identify key flow patterns that guide particles into ordered microstructures. Particle-scale phenomena responsible for the formation of microstructures will be determined by analyzing simulation results and comparing them with experiments under highly controlled conditions. Although the project will focus on emulsions of deformable drops, the project?s results will apply to spontaneous ordering in other systems with nonlinear particle interactions, such as suspensions of rigid particles in non-Newtonian fluids. Understanding the fundamental hydrodynamic mechanisms that govern self-assembling microstructures in confined flows could help practitioners design and process composite materials.