Related Experiment Video
Updated: Jun 23, 2026
11:03
An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Characterization of clusters in rapid granular flows.
R Brent Rice1, Christine M Hrenya
1Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, USA.
Summary
This study reveals new insights into granular flow clustering. Cluster prevalence decreases with higher particle concentrations, contrary to expectations, and is linked to particle interactions and system dissipation.
Area of Science:
- Physics
- Materials Science
- Fluid Dynamics
Background:
- Granular materials exhibit complex behaviors, including clustering, under shear flow.
- Understanding these phenomena is crucial for applications involving powders, grains, and other particulate matter.
Purpose of the Study:
- To investigate the clustering phenomenon in two-dimensional, rapid granular, simple shear flows.
- To develop and implement characterizations for monodisperse granular systems to gain physical insight.
Main Methods:
- Developed two characterizations for monodisperse granular systems.
- Identified a new feature in the radial distribution function for dissipative granular systems.
- Utilized a Gaussian filter based on center-to-center distance for concentration and temperature measurements.
Main Results:
- A novel long-scale minimum in the radial distribution function indicates average distances between cluster centers and dilute regions.
- Tighter cluster packing was observed at moderate particle concentrations and low restitution coefficients.
- Cluster prevalence unexpectedly decreased monotonically with increasing overall particle concentration, despite increased clustering at lower dissipation.
Conclusions:
- The study provides a new characterization of clustering in granular flows.
- Findings confirm that cluster prevalence increases with decreasing dissipation and clustered regions have lower temperatures.
- A surprising inverse relationship between cluster prevalence and overall particle concentration was discovered.
Related Concept Videos
01:24Rapidly Varying Flow
Rapidly varying flow (RVF) in open channels is characterized by abrupt changes in flow depth over a short distance, with the rate of depth change relative to distance often approaching unity. These flows are inherently complex due to their transient and multi-dimensional nature, making exact analysis difficult. However, approximate solutions using simplified models provide valuable insights into their behavior.Key Features of Rapidly Varying FlowRVF is commonly observed in scenarios involving...
01:20Characteristics of Fluids
When a force is applied parallel to the top surface of a solid, it resists the applied force due to the internal frictional forces between the layers of the solid known as shearing resistance. However, when the force is removed, the shearing forces restore the original shape of the solid. Other deformation forces also cause temporary changes in shape if the forces are not beyond a threshold magnitude. Solids tend to retain their shape, making the study of their rest and motion easier. Beyond...
01:31Characteristics of Fluids
Fluids differ from solids primarily in their molecular structure and stress response. Solids have tightly packed molecules with strong intermolecular forces, maintaining their shape and resisting deformation. In contrast, fluids have molecules spaced farther apart with weaker forces, allowing them to flow and deform easily.
Fluids, which include both liquids and gases, are substances that deform continuously under shearing stress. For example, water and oil are liquids with molecules that can...
Fluids, which include both liquids and gases, are substances that deform continuously under shearing stress. For example, water and oil are liquids with molecules that can...
01:26General External Flow Characteristics
The study of external flow is essential for creating structures and objects that interact efficiently and safely with moving fluids, such as air or water. When a body is immersed in a flowing fluid, it experiences two primary forces: drag, which opposes motion along the flow direction, and lift, which acts perpendicular to the flow. The shape, size, and orientation of the object influence these forces.Streamlined and Blunt Bodies in External FlowObjects in fluid flow are classified as...
01:29Gradually Varying Flow
Gradually varying flow (GVF) in open channels describes situations where water depth changes slowly along the channel due to factors like non-uniform bed slope, channel shape variations, or obstructions. This flow type occurs when the depth adjusts gradually to balance gravitational forces, shear forces, and energy requirements, resulting in a low rate of depth change.Characteristics of Gradually Varying FlowGVF is commonly observed in natural streams, rivers, and canals, where flow depth...
01:17Steady, Laminar Flow Between Parallel Plates
Understanding steady, laminar flow between parallel plates is essential for analyzing and designing flow in narrow rectangular channels, commonly found in various water conveyance and drainage systems. The Navier-Stokes equations govern fluid motion and are generally challenging to solve due to their nonlinearity. However, simplifications are possible in certain cases, like the steady laminar flow between parallel plates. For this scenario, we assume steady, incompressible, laminar flow.