Self-Driving and Merging Droplets on Wettability Gradient Surfaces: A Lattice Boltzmann Study

Authors : Mehmet Alptug Boylu, Umut Ceyhan

Pages : 464-473

Doi:10.19113/sdufenbed.1305602

View : 104 | Download : 79

Publication Date : 2023-12-25

Article Type : Research Paper

Abstract :Self-transport and control of droplets play an essential role in the development of microfluidic devices, self-cleaning, water harvesting, and heat transfer enhancement. Droplet manipulation without an external force can be accomplished if a wetting gradient is structured on surfaces. The contact angle hysteresis generates a driving force toward the more wetting side. If this force is balanced by the viscous stresses near moving contact lines, droplets on such surfaces may attain constant translational speed determined by this balance. The D2Q9 lattice Boltzmann method is employed for the simulation of the self-driven droplets on wettability gradient surfaces. By varying the surface energy and fluid viscosities, the behavior of single droplets on surfaces, their merging mechanism, and equilibrium shapes and motions within confined channels are studied systematically. If the droplet moves in a more viscous fluid, the droplet’s speed dependence on the wetting gradient is observed to weaken. For large aspect ratio channel flows, it is shown that two-dimensional prediction of the interface motion approaches the three-dimensional D3Q19 model computations.
Keywords : Arayüzey akışı, Temas hattı, Islanabilirlik gradyanı, Lattice Boltzmann metodu