BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Transition in energy spectrum for forced stratified turbulence - K
 imura\, Y (Nagoya)
DTSTART:20081003T103000Z
DTEND:20081003T110000Z
UID:TALK13875@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:Energy spectrum for forced stably stratified turbulence is inv
 estigated numerically by solving the 3D Navier-Stokes equations under the 
 Boussinesq approximation with stochastic forcing applied to the largest ve
 locity scales. Using pseudo-spectral simulations with 1024^3 grid points\,
  we could verify the transition in the vortex (horizontal) spectrum (as a 
 function of horizontal wave number) from $k_{perp}^{-3}$ to $k_{perp}^{-5/
 3}$. Meanwhile the wave spectra shows $k_{perp}^{-2}$ for the large scales
 \, and $k_{perp}^{-5/3}$ for the small scales. According to Carnevale {it 
 et.~al.}\, the transition wave number is understood as the Ozmidov scale w
 ith a correction by the coefficients of the buoyancy spectrum\, $E(k) =lp
 ha N^2k^{-3}$\, and the Kolmogorov spectrum\, $E(k)=C_Kpsilon^{2/3} k^{-5
 /3}$. By equating these spectra\, $k_b  im (lpha/C_K)^{3/4} qrt {N^3/ ps
 ilon}$ is obtained for the transition wavenumber. Our calculation shows\, 
 however\, that the vortex spectra at large scales seem to have the same sl
 ope irrespective of stratification\, which implies a possibility of a diff
 erent mechanism for producing the $k_{perp}^{-3}$ spectrum. We will discus
 s possibility that the spectrum corresponds to two-dimensional turbulence.
 \n\nReferece: Carnevale\,G.F. {it et.~al}: 2001 J.~Fluid Mech. {f 427} 20
 5--239. 
LOCATION:Seminar Room 1\, Newton Institute
END:VEVENT
END:VCALENDAR