Numerical simulations of emulsions in shear flows
Abstract
We present a modification of a recently developed volume of fluid method for multiphase problems, so that it can be used in conjunction with a fractional stepmethod and fast Poisson solver, and validate it with standard benchmark problems. We then consider emulsions of twofluid systems and study their rheology in a plane Couette flow in the limit of vanishing inertia. We examine the dependency of the effective viscosity on the volumefraction (from 10% to 30%) and the Capillary number (from 0.1 to 0.4) for the case of density and viscosity ratio 1. We show that the effective viscosity decreases with the deformation and the applied shear (shearthinning) while exhibits a nonmonotonic behavior with respect to the volume fraction. We report the appearance of a maximum in the effective viscosity curve and compare the results with those of suspensions of rigid and deformable particles and capsules. We show that the flow in the solvent is mostly a shear flow, while it is mostly rotational in the suspended phase; moreover this behavior tends to reverse as the volume fraction increases. Finally, we evaluate the contributions to the total shear stress of the viscous stresses in the two fluids and of the interfacial force between them.
 Publication:

arXiv eprints
 Pub Date:
 July 2018
 arXiv:
 arXiv:1807.01841
 Bibcode:
 2018arXiv180701841E
 Keywords:

 Physics  Fluid Dynamics