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The problem of capturing marginality in model reductions of turbulence

Author
Abstract
Reduced quasilinear and nonlinear (gradient-driven) models with scale separations, commonly used to interpret experiments and to forecast turbulent transport levels in magnetised plasmas, are tested against nonlinear models without scale separations (flux-driven). Two distinct regimes of turbulence -either above threshold or near marginal stability- are investigated with Boltzmann electrons. The success of reduced models hinges in particular on the reproduction of nonlinear fluxes. Good agreement between models is found above threshold, whilst reduced models significantly underpredict fluxes near marginality, overlooking mesoscale flow organisation and turbulence self-advection. Constructive prescriptions whereby to improve reduced models are discussed.
Year of Publication
2023
Journal
Plasma Physics and Controlled Fusion
Volume
65
Issue
5
Number of Pages
055012
DOI
10.1088/1361-6587/acc276
PId
0d4081c5a8c33c0f3b02bd714454ff2a
Alternate Journal
Plasma Phys. Control. Fusion
Label
OA
Attachment
Journal Article
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