A numerical study on viscoelastic droplet migration on substrates with wetting gradients*

The study of spontaneous motions of a droplet migrating due to substrate wettability gradient is extended to viscoelastic fluids using numerical simulations based on the multiphase-field model of OpenFOAM with new boundary conditions, ensuring correct contact angles at multiphase junctions. The migration speed and the shape of the droplet, dependent on the Weissenberg number, are examined along with other parameters studied previously.  For the parameter ranges studied it is found that the fluid elasticity affects the droplet motion indirectly more by changing the droplet footprint than other ways.