Numerical Modeling of Viscoelasticity in Particle Suspensions Using the Discrete Element Method

Area of Science:

• Multiphase flow dynamics
• Rheology of complex fluids
• Computational physics

Background:

• Particle suspensions exhibit complex rheological behavior due to interactions between distinct phases.
• Fluid-particle interfacial forces, such as lubrication, significantly influence macroscopic properties.
• Accurate modeling of viscoelasticity in suspensions is crucial for various industrial applications.

Purpose of the Study:

• To develop and validate a computational method for modeling fluid viscoelasticity in suspensions of spherical particles.
• To investigate the specific influence of fluid-particle interactions, particularly lubrication forces, on the system's viscoelastic response.
• To establish a framework for customizing particle-level interactions based on fundamental physical principles.

Main Methods:

• Coupled discrete element method (DEM) and computational fluid dynamics (CFD) simulations were employed.
• A simplified approach focused on non-adhesive elastic particle-particle contacts to isolate fluid-particle interactions.
• Simulations involved oscillatory flow in a three-dimensional domain, with and without particles, to differentiate effects.

Main Results:

• The model qualitatively reproduces the increase in storage modulus with increasing solid volume fraction.
• The dynamic moduli were shown to depend on the applied shear strain, consistent with experimental observations.
• The methodology successfully isolated the impact of fluid inertia and interfacial forces on viscoelasticity.

Conclusions:

• The DEM-CFD approach provides a versatile platform for simulating the rheology of particle suspensions.
• Customizing particle-level interactions based on first principles offers a powerful tool for understanding complex fluid behavior.
• This method enhances insights into modeling suspension rheology by focusing on fundamental material properties and interactions.