Related Experiment Video
Updated: Jul 13, 2026
11:03
An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Velocity statistics in dissipative, dense granular media.
David J Bray1, Michael R Swift, P J King
1School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom.
Summary
We studied velocity distributions in driven granular media using a random-force model. Highly dissipative systems show exponential tails due to single particle dynamics in dilute regions.
Area of Science:
- Physics
- Materials Science
- Statistical Mechanics
Background:
- Granular materials exhibit complex behaviors under external forces.
- Understanding particle velocity distributions is key to predicting macroscopic properties.
Purpose of the Study:
- Investigate velocity distributions in two-dimensional driven granular media.
- Analyze the influence of dissipation and packing fraction on these distributions.
- Explain the origin of exponential tails in highly dissipative systems.
Main Methods:
- Utilized a two-dimensional random-force model.
- Analyzed particle dynamics and velocity distributions.
- Developed a self-consistent kinetic theory.
Main Results:
- Velocity distribution shape depends on dissipation and packing fraction.
- Highly dissipative systems exhibit near-exponential velocity distribution tails.
- Exponential tails originate from single-particle dynamics in dilute regions under random forces.
Conclusions:
- The random-force model effectively describes velocity distributions in driven granular media.
- A self-consistent kinetic theory can explain the observed exponential tails.
More Related Videos
11:51Visually Based Characterization of the Incipient Particle Motion in Regular Substrates: From Laminar to Turbulent Conditions
Published on: February 22, 2018
09:00Visualization of Failure and the Associated Grain-Scale Mechanical Behavior of Granular Soils under Shear using Synchrotron X-Ray Micro-Tomography
Published on: September 29, 2019
Related Concept Videos
01:27Distribution of Molecular Speeds
The motion of molecules in a gas is random in magnitude and direction for individual molecules, but a gas of many molecules has a predictable distribution of molecular speeds. This predictable distribution of molecular speeds is known as the Maxwell-Boltzmann distribution. The distribution of molecular speeds in liquids is comparable to that of gases but not identical and can help to understand the phenomenon of the boiling and vapor pressure of a liquid. Consider that a molecule requires a...
01:23Steady, Laminar Flow in Circular Tubes
Hagen-Poiseuille flow describes a viscous fluid's steady, incompressible flow through a cylindrical tube with a constant radius R. This flow profile is often applied to understand fluid transport in narrow channels, such as capillaries. It serves as a foundational example of laminar flow. In this model, cylindrical coordinates (r,θ,z) are used to describe the radial (r), angular (θ), and axial (z) dimensions within the tube. For Hagen-Poiseuille flow, the velocity profile is purely axial,...
01:20Stokes' Law
Viscous forces, like friction, are intermolecular forces that resist the relative motion of molecules over each other. When a solid body moves through a liquid, viscous forces drag it in the opposite direction. The force's magnitude depends on the solid's shape and size, as well as its speed and the liquid's coefficient of viscosity, density and temperature.
The expression for the force on a solid spherical object in a fluid is called Stokes' law. Stokes' law is valid only for low Reynolds...
The expression for the force on a solid spherical object in a fluid is called Stokes' law. Stokes' law is valid only for low Reynolds...
01:17Viscosity
When water is poured into a glass, it falls freely and quickly, whereas if honey or maple syrup is poured over a pancake, it flows slowly and sticks to the surface of the container. This difference in the flow of different kinds of liquids arises due to the fluid friction between the liquid layers and the liquid and the surrounding material. This property of fluids is called fluid viscosity. In this example, water has a lower viscosity than honey and maple syrup.
The SI unit of viscosity is...
The SI unit of viscosity is...
01:27Viscosity
Viscosity is a property of fluids that measures their resistance to flow. It is influenced by factors such as the surface area of contact, the gradient of flow speed, and the fluid's viscosity constant, called the coefficient of viscosity. The coefficient of viscosity, also known as dynamic viscosity, is denoted by the symbol η. It determines the proportionality between the viscous force and the gradient of flow speed.Newton's law of viscosity states that the viscous force on a faster-moving...
01:19Viscosity of Fluid
Viscosity measures the resistance a fluid offers to flow and deformation. It results from internal friction between layers of fluid moving relative to one another. Dynamic viscosity, denoted by the Greek letter mu (μ), quantifies the force needed to move one fluid layer over another. For Newtonian fluids like water and air, the relationship between the shearing stress and the rate of shearing strain is linear, meaning their viscosity remains constant regardless of the applied stress.