Morphological classification and dynamics of a two-dimensional drop sliding on a vertical plate

Area of Science:

• Fluid Dynamics
• Interfacial Phenomena
• Computational Physics

Background:

• Understanding drop dynamics is crucial for various applications, including microfluidics and materials science.
• The behavior of a sliding drop involves complex interactions at the three-phase contact line.
• Previous studies often simplify the force balance and contact line dynamics.

Purpose of the Study:

• To numerically investigate the two-dimensional sliding of a drop on a plate under gravitational force.
• To analyze the morphologies and force balance governing the drop's motion.
• To identify and characterize different sliding modes based on gravitational and viscous effects.

Main Methods:

• Employed a numerical approach combining the lattice Boltzmann method and the phase field method.
• Successfully captured the intricate motion of the three-phase contact line.
• Analyzed the viscous shear stress distribution on the solid-liquid interface.

Main Results:

• Identified two fundamental sliding modes for the drop, dependent on gravity and viscosity.
• Discovered that viscous shear stress, particularly in the contact line region, plays a critical role.
• Observed that increased gravity leads to an additional shear force from a rear trail, stabilizing velocity.

Conclusions:

• The study provides insights into the physics of drop sliding, particularly the role of contact line shear stress.
• The findings are relevant for understanding both two-dimensional and three-dimensional drop behaviors.
• The numerical methods used are effective for simulating complex fluid interfaces and contact line phenomena.