Superadiabatic dynamical density functional theory for colloidal suspensions under homogeneous steady-shear

Area of Science:

• Soft Matter Physics
• Colloidal Science
• Non-equilibrium Statistical Mechanics

Background:

• Dynamical density functional theory (DDFT) is a key tool for studying colloidal systems.
• Understanding the rheology of colloidal suspensions out-of-equilibrium is crucial for many applications.
• Existing rheological models often simplify interparticle interactions and system dynamics.

Purpose of the Study:

• To introduce and apply the superadiabatic dynamical density functional theory (superadiabatic-DDFT) to colloidal systems under shear.
• To calculate steady-state properties like pair distribution functions and viscosity for bulk systems.
• To generalize existing rheological bulk theories for inhomogeneous colloidal systems.

Main Methods:

• Utilizing the superadiabatic-DDFT framework to model colloidal dynamics.
• Explicitly treating the dynamics of two-body correlations to account for viscous forces.
• Calculating steady-state pair distribution functions and viscosity under low shear rates.
• Developing an inhomogeneous generalization of the Russel and Gast rheological bulk theory.

Main Results:

• The study successfully calculates the steady-state pair distribution function and viscosity for bulk colloidal systems at low shear rates.
• An inhomogeneous generalization of a known rheological bulk theory is derived.
• A novel connection is established between DDFT-based methods and established rheological theories.

Conclusions:

• Superadiabatic-DDFT provides a robust framework for studying non-equilibrium colloidal dynamics.
• The research bridges the gap between microscopic DDFT approaches and macroscopic rheological theories.
• This work offers new theoretical tools for understanding and predicting the behavior of colloidal suspensions under flow.