title: Non-Newtonian flow effects on the coalescence and mixing of initially stationary droplets of shear-thinning fluids.
abstract: The coalescence of two initially stationary droplets of shear-thinning fluids in a gaseous environment is investigated numerically using the lattice Boltzmann method, with particular interest in non-Newtonian flow effects on the internal mixing subsequent to coalescence. Coalescence of equal-sized droplets, with one being Newtonian while the other is non-Newtonian, leads to the non-Newtonian droplet wrapping around the Newtonian one and hence minimal fine-scale mixing. For unequal-sized droplets, mixing is greatly promoted if both droplets are shear-thinning. When only one of the droplets is shear-thinning, the non-Newtonian effect from the smaller droplet is found to be significantly more effective than that from the larger droplet in facilitating internal jetlike mixing. Parametric study with the Carreau-Yasuda model indicates that the phenomena are universal to a wide range of shear-thinning fluids, given that the extent of shear thinning reaches a certain level, and the internal jet tends to be thicker and develops more rapidly with increasing extent of the shear-thinning effect.
authors.affiliation: State Key Laboratory of Engines, Tianjin University, Tianjin, China.|Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong.
authors.forename: Kai
authors.initials: K
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Engines, Tianjin University, Tianjin, China.
authors.forename: Tianyou
authors.initials: T
authors.lastname: Wang
authors.affiliation: Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Center for Combustion Energy, Tsinghua University, Beijing, China.|Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey, USA.
authors.forename: Chung K
authors.initials: CK
authors.lastname: Law