A new model for the bouncing regime boundary in binary droplet collisions Physics of Fluids 31, 027105 (2019); https://doi.org/10.1063/1.5085762Post-collision hydrodynamics of droplets on cylindrical bodies of variant convexity and wettability Physics of Fluids 31, 022008 (2019); https://doi.
ABSTRACTThe lubrication flow of a Herschel-Bulkley fluid in a long asymmetric channel, the walls of which are described by two arbitrary functions h 1 (x) and h 2 (x) such that h 1 (x) < h 2 (x) and h 1 (x) + h 2 (x) are linear, is solved extending a recently proposed method, which avoids the lubrication paradox approximating satisfactorily the correct shape of the yield surface at zero order [P. Panaseti et al., "Pressure-driven flow of a Herschel-Bulkley fluid with pressure-dependent rheological parameters," Phys. Fluids 30, 030701 (2018)]. Both the consistency index and the yield stress are assumed to be pressure-dependent. Under the lubrication approximation, the pressure at zero order is a function of x only, is decoupled from the velocity components, and obeys a first-order integro-differential equation. An interesting feature of the asymmetric flow is that the unyielded core moves not only in the main flow direction but also in the transverse direction. Explicit expressions for the two yield surfaces defining the asymmetric unyielded core are obtained, and the two velocity components in both the yielded and unyielded regions are calculated by means of closed-form expressions in terms of the calculated pressure and the two yield surfaces. The method is applicable in a range of Bingham numbers where the unyielded core extends from the inlet to the outlet plane of the channel. Semi-analytical solutions are derived in the case of an asymmetric channel with h 1 = 0 and linearly varying h 2 . Representative results demonstrating the effects of the Bingham number and the consistency-index and yield-stress growth numbers are discussed.Published under license by AIP Publishing. https://doi.