Many-body dissipative particle dynamics simulation of Newtonian and non-Newtonian nanodroplets spreading upon flat and textured substrates

Abstract

To deposit droplets on substrates efficiently is critical for many technological and industrial applications, which requires a systematic understanding of the droplet spreading process. In the paper, mesoscopic modeling of viscous nanodroplets spreading on different solid surfaces has been conducted by many-body dissipative particle dynamics. The influence of fluid viscosity has been particularly analyzed by changing the interaction parameters and the maximum droplet spreading diameter has been obtained. The dimensionless maximum spreading diameter is correlated to the Reynolds numbers (Re) and Weber numbers (We) as βmax = 0.7Re0.1445We0.066. With the droplets partially attached by polymer chains to exhibit a shear-thinning non-Newtonian property, we demonstrate that the maximum spreading diameters are extremely different under a small initial kinetic energy, and gradually become consistent at a larger Weber number. Investigation of the spreading process on the intricate surfaces decorated by regular pillared structures shows a special expansion effect to improve the intrinsic wetting characteristic of the substrates, which is strongly controlled by the surface fraction of the pillared structures. Moreover, it is found that the fluid viscosity can profoundly affect the rebounding behavior of the droplet.