Related Experiment Video
Updated: Nov 23, 2025
08:25
Measurements of Local Instantaneous Convective Heat Transfer in a Pipe - Single and Two-phase Flow
Published on: April 30, 2018
7.4K
Second-Order Phase Transition in Counter-Rotating Taylor-Couette Flow Experiment.
Kerstin Avila1,2,3, Björn Hof3
1Faculty of Production Engineering, University of Bremen, Badgasteiner Strasse 1, 28359 Bremen, Germany.
Entropy (Basel, Switzerland)
|January 5, 2021
Summary
Turbulence in shear flows can coexist with laminar flow. This study shows the transition to laminar flow in circular Couette geometry is continuous, unlike previous findings, suggesting finite size effects in earlier research.
Area of Science:
- Fluid dynamics
- Turbulence research
- Phase transitions in complex systems
Background:
- Turbulence and laminar flow coexist in many shear flows, with turbulence receding as flow speed decreases.
- The nature of this transition (first or second order) is crucial for understanding turbulence dynamics.
- Previous studies on Couette flow suggested a discontinuous transition, potentially due to limitations.
Purpose of the Study:
- To investigate the order of the phase transition between turbulent and laminar flow in a circular Couette geometry.
- To determine if the transition is continuous or discontinuous.
- To assess the influence of system size on the observed transition dynamics.
Main Methods:
- Experimental realization of a circular Couette flow between concentric cylinders.
- Measurements conducted over large aspect ratios and extended observation times.
- Analysis of the turbulent fraction as a function of flow speed (Reynolds number).
Main Results:
- The transition from turbulent to laminar flow in the circular Couette geometry was observed to be continuous.
- This finding contrasts with previous studies on planar Couette flow, indicating potential finite size effects.
- The study highlights the need for even larger system sizes to fully characterize the transition and its universality class.
Conclusions:
- The transition to laminar flow in circular Couette shear flows is continuous.
- Finite size effects likely influenced previous observations of a discontinuous transition.
- Further research with larger systems is needed to explore connections to directed percolation universality.
Related Concept Videos
01:22Couette Flow
664
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...
664
01:17Steady, Laminar Flow Between Parallel Plates
583
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.
583
01:23Steady, Laminar Flow in Circular Tubes
701
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,...
701
01:28Irrotational Flow
740
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:
740
01:16Bernoulli's Equation for Flow Normal to a Streamline
1.1K
Bernoulli's equation for flow normal to a streamline explains how pressure varies across curved streamlines due to the outward centrifugal forces induced by the fluid's curvature. The pressure is higher on the inner side of the curve, near the center of curvature, and decreases outward to balance these centrifugal forces.
The pressure difference depends on the fluid's velocity and radius of curvature. The pressure variation is minimal in flows with nearly straight streamlines. However, the...
The pressure difference depends on the fluid's velocity and radius of curvature. The pressure variation is minimal in flows with nearly straight streamlines. However, the...
1.1K
01:30Bernoulli's Equation for Flow Along a Streamline
1.2K
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:
1.2K