Effect of Suspended Particles and Polymers on the Deformation of Droplets

We investigate the effect of viscous and elastic forces and the interfacial wetting of nanoparticles and polymers on the deformation of a droplet under shear deformation. We model the fluid phase via a free energy based binary lattice-Boltzmann model while for the particles we use a point particle approach. The particles are chained together through a finitely extensible spring potential and are coupled to the fluid through frictional and wetting forces. Both the polymers and dispersed particles display a complex and nonmonotonic behavior with respect to capillary number. In addition the polymers also exhibit surprising behavior with a change in the contour length; i.e. the Weissenberg number. We identify where the viscous, elastic and wetting effects are most effective in reducing the deformation and correlate this behavior with the polymer size, confinement effects, virial stress and flow field inside the droplet.