Self-organization in the flow of complex fluids (colloid and polymer systems). Part 2: Theoretical models

Area of Science:

• Rheology
• Fluid Dynamics
• Materials Science

Background:

• Complex fluids display flow-induced transitions affecting internal structure and symmetry.
• Understanding these transitions is crucial for predicting fluid behavior under stress.

Purpose of the Study:

• To review theoretical models and approaches for analyzing flow instabilities and patterns in complex fluids.
• To focus on fluid models exhibiting vortex and banding flow structures at high shear rates.

Main Methods:

• Analysis of theoretical models for complex fluid flow.
• Examination of fluid behavior governed by Reynolds and Weissenberg (or Deborah) numbers.
• Description of secondary flow patterns in viscometric flows.

Main Results:

• The Oldroyd-B fluid model reveals vortex and banding flow structures.
• Complex fluids can form coexisting shear bands with distinct rheological properties.
• Shear banding is characteristic of fluids with non-monotonous flow curves.

Conclusions:

• Theoretical models provide insights into complex fluid flow instabilities.
• Shear banding is a key phenomenon in non-Newtonian fluid dynamics.
• Further exploration of shear banding in complex fluids is ongoing.