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SUMMARY:The dynamics of stratified horizontal shear flows at low Péclet n
 umber - Laura Cope\, University of Cambridge\, UK
DTSTART:20210604T150000Z
DTEND:20210604T160000Z
UID:TALK160759@talks.cam.ac.uk
CONTACT:James Parke
DESCRIPTION:Stratified flows are ubiquitous\; examples include atmospheres
  and oceans in geophysics and stellar interiors in astrophysics. The inter
 action of a stable stratification with a background velocity distribution 
 can develop into stratified turbulence\, key to transport processes in man
 y systems. Geophysical flows\, in which the Prandtl number Pr ∼ O(1)\, a
 re often strongly stratified\, nevertheless\, turbulence still occurs. Den
 sity layering is key to understanding the properties of this ‘layered an
 isotropic stratified turbulence’ (LAST) regime that is characterised by 
 anisotropic length scales and velocity fields. Conversely\, Pr ≪ 1 for a
 strophysical flows\, inhibiting the formation of density layers. This sugg
 ests that LAST dynamics cannot occur\, raising the question of whether ana
 logous or fundamentally different regimes exist in the limit of strong the
 rmal diffusion. This study addresses this question for the case of a verti
 cally stratified\, horizontally-forced Kolmogorov flow using a combination
  of linear stability theory and direct numerical simulations. Four distinc
 t dynamical regimes emerge\, depending upon the strength of the background
  stratification. By considering dominant balances in the governing equatio
 ns\, we derive scaling laws which explain the empirical observations.
LOCATION:GKB 100 Fluid Mechanics Webinar Series
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