Dilute Polymer Droplets Show Generalized Wetting Dynamics via an Average Viscosity.

Area of Science:

• Fluid Dynamics
• Materials Science
• Rheology

Background:

• Dynamic wetting models for non-Newtonian fluids are limited.
• Existing models often fail to capture complex rheological behaviors.

Purpose of the Study:

• To develop and validate a generalized model for the dynamic wetting of non-Newtonian shear-thinning fluids.
• To improve predictions of droplet spreading dynamics for complex fluids.

Main Methods:

• Experimental analysis of 12 shear-thinning fluids (dilute polymer solutions).
• Application of power-law and Carreau-Yasuda models.
• Development of a semi-analytical spreading model using average viscosity.

Main Results:

• Dynamic contact angle can be generalized using average viscosity.
• The proposed model accurately predicts the basal radius of spreading non-Newtonian droplets.
• Average viscosity defines a spreading time scale, creating a master spreading curve for various fluids.

Conclusions:

• The generalized model effectively predicts dynamic wetting for non-Newtonian shear-thinning fluids.
• This work provides a valuable tool for understanding and controlling fluid behavior in industrial processes.
• The findings have broad implications for applications involving complex fluid dynamics.