Rheological similarities between dense self-propelled and sheared particulate systems.

Area of Science:

• Physics
• Rheology
• Soft Matter Physics

Background:

• Traditional models use constant propulsion force (CPF) for self-propelled particles.
• CPF models face limitations in simulating quasistatic flows of yield stress fluids due to finite system sizes.

Purpose of the Study:

• To develop and validate a novel constant propulsion velocity (CPV) approach for modeling self-propelled particles.
• To investigate quasistatic flows of yield stress fluids using the CPV method.
• To explore the connection between self-propulsion and shear phenomena.

Main Methods:

• Developed a CPV method for particle propulsion, contrasting it with the conventional CPF approach.
• Simulated cyclic self-propulsion to study force evolution with particle displacement in quasistatic flow regimes.
• Mapped propulsion force and velocity to shear stress and shear rate to compare rheological behaviors.

Main Results:

• The CPV approach aligns with CPF in flowing regimes but excels in accessing quasistatic flows.
• Observed rheological behaviors in self-propelled systems analogous to sheared systems, including yield force gaps, force overshoots, and reversible-irreversible transitions.
• Identified propulsion bands in plastic flows, similar to those seen in sheared systems.

Conclusions:

• The CPV method provides a powerful tool for studying yield stress fluids and quasistatic phenomena.
• Self-propelled systems exhibit rheological behaviors that closely mirror those of sheared systems.
• There are significant underlying connections between self-propulsion dynamics and shear-induced phenomena.