Related Experiment Video
Updated: Nov 27, 2025
10:12
Analyzing Mixing Inhomogeneity in a Microfluidic Device by Microscale Schlieren Technique
Published on: June 12, 2015
9.3K
Intermittency and Critical Scaling in Annular Couette Flow
Kazuki Takeda1, Yohann Duguet2, Takahiro Tsukahara1
1Department of Mechanical Engineering, Tokyo University of Science, Chiba 278-8510, Japan.
Entropy (Basel, Switzerland)
|December 8, 2020
Summary
Turbulence onset in subcritical shear flows was studied in annular Couette flow. A novel regime was found for small radius ratios, distinct from plane Couette flow dynamics.
Area of Science:
- Fluid dynamics
- Turbulence
- Critical phenomena
Background:
- Subcritical shear flows exhibit puzzling turbulence onset.
- Annular Couette flow with an inner moving rod is a relevant model system.
Purpose of the Study:
- Investigate turbulence onset in annular Couette flow.
- Identify novel flow regimes and analyze finite-size effects.
Main Methods:
- Direct numerical simulation of fluid flow.
- Analysis of finite-size effects by increasing domain perimeter.
- Statistical analysis of turbulent fraction and laminar gap distributions.
Main Results:
- A novel turbulent regime was identified for small radius ratios, lacking oblique bands.
- Finite-size effects were analyzed, showing a cross-over in scaling for wider domains.
- Turbulence onset dynamics resemble one-dimensional directed percolation with confinement frustration.
Conclusions:
- Annular Couette flow reveals a new turbulence regime distinct from plane Couette flow.
- Finite-size effects significantly influence turbulence statistics and scaling.
- The findings link fluid turbulence to concepts from statistical physics, like directed percolation.
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
9.0K
12:26Fabrication, Operation and Flow Visualization in Surface-acoustic-wave-driven Acoustic-counterflow Microfluidics
Published on: August 27, 2013
17.5K
Related Concept Videos
01:22Couette Flow
676
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...
676
01:17Steady, Laminar Flow Between Parallel Plates
593
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.
593
01:23Steady, Laminar Flow in Circular Tubes
713
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,...
713
01:30Bernoulli's Equation for Flow Along a Streamline
1.3K
Bernoulli's equation relates the energy conservation in a fluid moving along a streamline. The equation applies to incompressible and inviscid fluids under steady flow. For such a flow, Newton's second law is applied to a small fluid element, which experiences forces due to pressure differences, gravity, and velocity variations. The force balance leads to the following form of Bernoulli's equation:
1.3K
01:24Rapidly Varying Flow
268
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...
268
01:07Laminar and Turbulent Flow
10.1K
Fluid dynamics is the study of fluids in motion. Velocity vectors are often used to illustrate fluid motion in applications like meteorology. For example, wind—the fluid motion of air in the atmosphere—can be represented by vectors indicating the speed and direction of the wind at any given point on a map. Another method for representing fluid motion is a streamline. A streamline represents the path of a small volume of fluid as it flows. When the flow pattern changes with time, the...
10.1K