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Related Experiment Video

Updated: Mar 22, 2026

Experimental Investigation of Secondary Flow Structures Downstream of a Model Type IV Stent Failure in a 180&#176; Curved Artery Test Section
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Large-scale flow generation by inhomogeneous helicity.

N Yokoi1, A Brandenburg2

  • 1Institute of Industrial Science, University of Tokyo, Tokyo, Japan.

Physical Review. E
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Summary
This summary is machine-generated.

Investigating kinetic helicity in rotating turbulence reveals that inhomogeneous helicity gradients drive large-scale flows. This confirms the helicity effect for flow generation, suggesting vortex dynamos in incompressible turbulence.

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Area of Science:

  • Fluid Dynamics
  • Turbulence Theory
  • Magnetohydrodynamics (MHD)

Background:

  • Kinetic helicity, the correlation between velocity and vorticity, influences turbulent momentum transport.
  • Inhomogeneous helicity gradients can potentially generate mean flows.

Purpose of the Study:

  • To investigate the effect of kinetic helicity on turbulent momentum transport.
  • To examine the inhomogeneous helicity effect using direct numerical simulations.
  • To confirm the possibility of vortex dynamos in incompressible turbulence.

Main Methods:

  • Direct numerical simulations (DNS) of rotating turbulence.
  • Application of external forcing to sustain nonuniform helicity.
  • Analysis of Reynolds stress and large-scale flow generation.

Main Results:

  • Spatial distribution of Reynolds stress aligns with helicity gradients and angular velocity.
  • A large-scale flow is generated parallel to the angular velocity vector.
  • Homogeneous turbulent helicity does not induce such large-scale flows.

Conclusions:

  • Confirms the validity of the inhomogeneous helicity effect in generating large-scale flows.
  • Suggests that vortex dynamos are possible in incompressible turbulence without baroclinicity.
  • Highlights the role of kinetic helicity in turbulent momentum and flow generation.