Hydrodynamic theory of forced dewetting

Area of Science:

• Fluid dynamics
• Surface science
• Wetting phenomena

Background:

• The study of wetting and dewetting phenomena is crucial in various scientific and industrial applications.
• A key problem involves solids being withdrawn from liquid baths, leading to dewetting.
• A critical speed exists, beyond which the solid surface transitions from dry to wetted.

Purpose of the Study:

• To provide the first theoretical explanation for the hydrodynamic origin of the dewetting transition.
• To explain the classical prediction by Derjaguin and Levi regarding critical speed in dewetting.
• To investigate the conditions for instability when the static meniscus shape approaches that of a perfectly wetting fluid.

Main Methods:

• Theoretical analysis of fluid dynamics at the three-phase contact line.
• Investigating the matching of the highly curved contact line region to the far-field static meniscus profile.
• Examining the hydrodynamic instability governing the dewetting process.

Main Results:

• Demonstrated that the transition from a dry to a wetted solid is of hydrodynamic origin.
• Provided a theoretical explanation for the critical speed phenomenon in dewetting.
• Identified that instability occurs when the static meniscus shape mimics that of a perfectly wetting fluid.

Conclusions:

• The critical speed in dewetting is a consequence of hydrodynamic instability.
• The theoretical framework explains the transition from a dry to a wetted solid surface.
• Understanding these dynamics is key for controlling liquid film deposition on withdrawing solids.