Relative dispersion in generalized twodimensional turbulence
type de publication 
article dans une revue internationale avec comité de lecture 
date de publication 
2017 
auteur(s) 
Foussard Alexis; Berti Stefano; Perrot Xavier; Lapeyre Guillaume 
journal (abréviation) 
Journal of Fluid Mechanics (J Fluid Mech) 
volume (numéro) 
821 
 
pages 
358 – 383 
résumé 
The statistical properties of turbulent fluids depend on how local the energy transfers among scales are, i.e. whether the energy transfer at some given scale is due to the eddies at that particular scale, or to eddies at larger (nonlocal) scale. This locality in the energy transfers may have consequences for the relative dispersion of passive particles. In this paper, we consider a class of generalized twodimensional flows (produced by the socalled $unicode[STIX]{x1D6FC}$ turbulence models), theoretically possessing different properties in terms of locality of energy transfers. It encompasses the standard barotropic quasigeostrophic (QG) and the surface quasigeostrophic (SQG) models as limiting cases. The relative dispersion statistics are examined, both as a function of time and as a function of scale, and compared to predictions based on phenomenological arguments assuming the locality of the cascade. We find that the dispersion statistics follow the predicted values from local theories, as long as the parameter $unicode[STIX]{x1D6FC}$ is small enough (dynamics close to that of the SQG model), for sufficiently small initial pair separations. In contrast, nonlocal dispersion is observed for the QG model, a robust result when looking at relative displacement probability distributions. However, we point out that spectral energy transfers do have a nonlocal contribution for models with different values of $unicode[STIX]{x1D6FC}$ , including the SQG case. This indicates that locality/nonlocality of the turbulent cascade may not always imply locality/nonlocality in the relative dispersion of particles and that the selfsimilar nature of the turbulent cascade is more appropriate for determining the relative dispersion locality. 
mots clés 
geophysical and geological flows geostrophic turbulence mixing and dispersion 
lien 

Exporter la citation au format
CSV (pour Excel)
ou
BiBTeX (pour LaTeX).