0379765 - ÚMCH 2013 RIV US eng J - Journal Article
Fortelný, Ivan - Jůza, Josef
Modeling of the influence of matrix elasticity on coalescence probability of colliding droplets in shear flow.
Journal of Rheology. Roč. 56, č. 6 (2012), s. 1393-1411. ISSN 0148-6055. E-ISSN 1520-8516
R&D Projects: GA ČR GAP106/11/1069
Institutional research plan: CEZ:AV0Z40500505
Institutional support: RVO:61389013
Keywords : coalescence * polymer blends * viscoelasticity
Subject RIV: BK - Fluid Dynamics
Impact factor: 2.795, year: 2012

The theory of shear-flow-induced coalescence of monodisperse Newtonian droplets in Newtonian and viscoelastic (described by the Maxwell model) matrices has been derived. Changes in flattening of droplets during coalescence are considered. Calculated dependences on the system parameters of probability, Pc, that the droplet collision is followed by their fusion for Newtonian systems agree qualitatively with the Rother–Davis theory [Phys. Fluids 13, 1178–1190, (2001)]. Values of Pc for a certain set of parameters are substantially affected by the model used to describe mobility of the interface. It has been found that increasing elasticity (relaxation time) of the matrix leads to decreasing Pc irrespective of mobility of the interface. This decrease is small for short relaxation times but pronounced for long relaxation times. The shapes of the dependences of Pc on the droplet radii and the shear rate are similar for systems with a Newtonian matrix but differ qualitatively for systems with a viscoelastic matrix. Results of the theory show that Pc for viscous and viscoelastic matrices can be semiquantitatively approximated by a product of probability for spherical droplets and probability for highly flattened droplets, calculated from Janssen’s theory [“Dynamics of liquid–liquid mixing,” Ph.D. thesis, Eindhoven University of Technology, Eindhoven, The Netherlands, 1993] for a viscous system.
Permanent Link: http://hdl.handle.net/11104/0007116