Mean force and fluctuations on a wall immersed in a sheared granular flow

Area of Science:

• Physics
• Engineering
• Computational Science

Background:

• Granular flows are ubiquitous in nature and industry.
• Understanding forces on boundaries is crucial for predicting granular material behavior.
• Previous studies often lack comprehensive analysis across various flow regimes.

Purpose of the Study:

• To investigate the mean force and force fluctuations on a rigid wall in sheared and confined granular flow.
• To explore the relationship between boundary conditions and wall forces.
• To identify distinct granular flow regimes based on force characteristics.

Main Methods:

• Numerical simulations using the discrete element method (DEM).
• Development of a periodic immersed-wall system for controlled simulations.
• Analysis of grain-wall contact force distributions and time series autocorrelation.

Main Results:

• Mean wall pressure is a monotonic function of the boundary macroscopic inertial number.
• Force fluctuations decrease and distributions transition from log-normal to Gaussian as inertial number lowers.
• System memory in force transmission observed at low inertial numbers for shorter systems.
• Contact force distributions remain invariant above a critical inertial number.

Conclusions:

• The study successfully identifies transitions between quasistatic, dense inertial, and collisional granular flow regimes.
• The boundary macroscopic inertial number is a key parameter governing granular flow behavior at walls.
• Force distribution analysis provides insights into the micro-mechanical behavior of granular materials.