Characterizing Dissipation in Fluid-Fluid Displacement Using Constant-Rate Spontaneous Imbibition

Area of Science:

• Fluid dynamics
• Interface science
• Microfluidics

Background:

• Fluid displacement in confined environments involves energy dissipation.
• Dissipation occurs both within the fluid bulk and at the fluid-interface (contact line).
• Understanding the relative contribution of these dissipation mechanisms is crucial for accurate modeling.

Purpose of the Study:

• To experimentally investigate the relative contributions of bulk and contact line dissipation during fluid displacement.
• To analyze the dynamic contact angles of menisci involved in the displacement process.
• To provide insights for macroscopic descriptions of multiphase flows.

Main Methods:

• Novel experimental setup for constant-rate spontaneous imbibition.
• Introduction of a viscous oil slug to control fluid displacement in a capillary tube.
• Theoretical analysis of dynamic contact angles.

Main Results:

• A significant fraction of energy dissipation occurs near the contact line.
• Experimental observations are rationalized by theoretical analysis of dynamic contact angles.
• The study quantifies the importance of contact line dissipation.

Conclusions:

• Contact line dissipation plays a major role in fluid displacement within confined geometries.
• Results have implications for multiphase flow modeling in microfluidic devices and porous media.
• The findings advance the understanding of fundamental fluid dynamics at small scales.