Related Experiment Video
Updated: Nov 29, 2025
08:42
Challenges in Rheological Characterization of Highly Concentrated Suspensions — A Case Study for Screen-printing Silver Pastes
Published on: April 10, 2017
20.3K
Particle flow rate in silos under rotational shear
D Hernández-Delfin1, T Pongó1, K To2
1Departamento de Física y Matemática Aplicada, Universidad de Navarra, P.O. Box 31080, Navarra, Spain.
Physical Review. E
|November 20, 2020
Summary
This study numerically reproduces granular flow in a rotating silo. For small outlets, flow rate increases with rotation; for larger ones, it shows nonmonotonic behavior due to density changes.
Area of Science:
- Physics
- Granular Mechanics
- Fluid Dynamics
Background:
- Granular flow in silos is crucial for industrial processes.
- Previous experiments showed complex flow rate behaviors with rotating silo bases.
- Understanding these behaviors requires detailed numerical analysis.
Purpose of the Study:
- To numerically reproduce and analyze granular flow in a rotating cylindrical silo.
- To investigate the relationship between rotational frequency and mass flow rate for different outlet sizes.
- To elucidate the underlying physical mechanisms driving the observed flow patterns.
Main Methods:
- Numerical simulation of granular flow using a coarse-graining technique.
- Calculation of macroscopic fields: density, momentum, and stress tensor.
- Decomposition of mass flux into velocity and density components.
- Analysis of kinetic stress distribution and system dilatancy.
Main Results:
- Numerical results match experimental findings on mass flow rate (Q) versus rotational frequency (f).
- Small outlet diameters show monotonic Q increase with f; larger diameters show nonmonotonic behavior.
- Flow pattern transitions from funnel flow to mass flow correlate with discharge changes.
- Nonmonotonic momentum behavior is attributed to density variations, not velocity changes.
- Increasing rotational shear enhances kinetic pressure and dilatancy for small orifices, increasing flow rate.
- Nonmonotonic kinetic pressure changes for large orifices explain the nonmonotonic flow rate.
Conclusions:
- The study confirms the complex interplay between rotational shear, density, and granular flow rate.
- Numerical simulations provide a detailed understanding of flow pattern transitions and their impact on discharge.
- Kinetic stress and dilatancy play key roles in modulating granular flow behavior in rotating silos.
Related Concept Videos
01:28Pipe Flowrate Measurement: Problem Solving
685
A spray tank system is engineered to uniformly distribute a pest-control liquid across plants by using a pressurized mechanism. The tank, pressurized to 150 kPa, holds the pesticide at a height of 0.80 meters. Liquid flows from the tank through a 1.9 meter pipe with a diameter of 0.015 meters, angled at 0.698 radians, ultimately reaching a 0.007 meter nozzle that sprays the pesticide. Accurate calculation of the system's flow rate is crucial to ensure uniform application, and this is achieved...
685
01:22Couette Flow
692
Couette flow represents the flow of fluid between two parallel plates, with one plate fixed and the other moving with a constant velocity. This configuration allows for a simplified analysis using the Navier-Stokes equations, which govern fluid motion under conditions of viscosity and incompressibility. For Couette flow, the assumptions include a steady, laminar, incompressible flow with a zero-pressure gradient in the flow direction. This flow type is beneficial for understanding shear-driven...
692
01:17Steady, Laminar Flow Between Parallel Plates
614
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.
614
01:23Steady, Laminar Flow in Circular Tubes
733
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,...
733
01:18Newtonian Fluid: Problem Solving
685
Newtonian fluids exhibit a constant viscosity, meaning their shear stress and shear strain rate are directly proportional. This property ensures a predictable and stable response to applied forces, maintaining a linear relationship between force and flow. Examples include water, air, and light oils, consistently demonstrating this proportional behavior regardless of external conditions.
A velocity gradient forms within the fluid when a Newtonian fluid is placed between two parallel plates, with...
A velocity gradient forms within the fluid when a Newtonian fluid is placed between two parallel plates, with...
685
01:28Irrotational Flow
765
Irrotational flow is characterized by fluid motion where particles do not rotate around their axes, resulting in zero vorticity. For a flow to be irrotational, the curl of the velocity field must be zero. This imposes specific conditions on velocity gradients. For instance, to maintain zero rotation about the z-axis, the gradient condition:
765