Modeling the Microstructure and Stress in Dense Suspensions under Inhomogeneous Flow

Area of Science:

• Rheology
• Fluid Dynamics
• Materials Science

Background:

• Dense suspensions often deviate from conventional homogeneous rheology under flow.
• Observed phenomena include flowing regions with friction below yielding and volume fractions above jamming criteria.

Purpose of the Study:

• To explain the underlying physics of dense suspension behavior in inhomogeneous flow.
• To incorporate shear rate fluctuations into a tensor model for microstructure and stress.

Main Methods:

• Development and application of a tensor model for microstructure and stress.
• Inclusion of shear rate fluctuations into the existing tensor model.
• Analysis of inhomogeneous flow problems using the modified model.

Main Results:

• The modified tensor model qualitatively reproduces particle-based simulation results.
• The model successfully captures the complex behavior of dense suspensions in inhomogeneous flow.
• Demonstration of how shear rate fluctuations influence macroscopic friction and volume fraction.

Conclusions:

• Shear rate fluctuations are critical for understanding dense suspension rheology in inhomogeneous flows.
• The proposed tensor model provides a viable framework for predicting suspension behavior.
• The findings challenge conventional homogeneous rheological assumptions for dense suspensions.