Dynamic Behaviors of Droplet Transport on Substrates under External Forces: A Many-Body Dissipative Particle Dynamics Study

Abstract Mesoscopic droplet transport has garnered significant attention and extensive research owing to its profound significance in diverse practical applications. In this work, many-body dissipative particle dynamics (MDPD) is employed to investigate the dynamic displacement behavior of droplets. Moving and static droplets are placed side by side on the left substrate. A constant body force drives the moving droplet forward, which eventually coalesces with the static one into a single merged droplet. The effects of the interdroplet attraction parameter, external driving force magnitude, and droplet radius are systematically analyzed. A smaller interdroplet attraction parameter promotes more significant rearrangement and homogeneous dispersion of two particles over time. The merged droplet tends to form a spherical shape, and the displacement stability is also enhanced as the attraction coefficient decreases. A larger external driving force causes more obvious stretching deformation of the merged droplet. The results also reveal a positive correlation between the external force and both the velocity and kinetic energy of the merged droplet. The velocity and kinetic energy of the merged droplet increase with the rising radius of the moving droplet but decrease as the static droplet size increases. A larger moving droplet weakens the homogeneous dispersion of the two particles and induces more significant necking behavior of the merged droplet. In contrast, increasing the static droplet size contributes to a more spherical droplet shape and more stable transport during displacement. These findings contribute to the fundamental understanding of droplet manipulation and provide a basis for further investigations on enhanced oil recovery and microfluidic systems.