Subcritical transition to turbulence in quasi-two-dimensional shear flows

The transition to turbulence in conduits is among the longest-standing problems in fluid mechanics. Challenges in producing or saving energy hinge on understanding promotion or suppression of turbulence. While a global picture based on an intrinsically 3-D subcritical mechanism is emerging for 3-D t...

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Bibliographic Details
Published in:Journal of fluid mechanics 2023-05, Vol.963, Article R3
Main Authors: Camobreco, Christopher J., Pothérat, Alban, Sheard, Gregory J.
Format: Article
Language:English
Subjects:
Blankets (fusion reactors)
Boundary conditions
Dimensions
Direct numerical simulation
Eigenvalues
Energy conservation
Energy consumption
Fluid dynamics
Fluid flow
Fluid mechanics
Friction
Fusion reactors
JFM Rapids
Laminar flow
Magnetic field
Magnetic fields
Nuclear fusion
Reynolds number
Shear flow
Stability analysis
Turbulence
Turbulent flow
Two dimensional flow
Velocity
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Summary:The transition to turbulence in conduits is among the longest-standing problems in fluid mechanics. Challenges in producing or saving energy hinge on understanding promotion or suppression of turbulence. While a global picture based on an intrinsically 3-D subcritical mechanism is emerging for 3-D turbulence, subcritical turbulence is yet to even be observed when flows approach two dimensions, e.g. under intense rotation or magnetic fields. Here, stability analysis and direct numerical simulations demonstrate a subcritical quasi-two-dimensional (quasi-2-D) transition from laminar flow to turbulence, via a radically different 2-D mechanism to the 3-D case, driven by nonlinear Tollmien–Schlichting waves. This alternative scenario calls for a new line of thought on the transition to turbulence and should inspire new strategies to control transition in rotating devices and nuclear fusion reactor blankets.
ISSN:0022-1120
1469-7645
DOI:10.1017/jfm.2023.345