Lab Home | Phone | Search
Center for Nonlinear Studies  Center for Nonlinear Studies
 Home 
 People 
 Current 
 Affiliates 
 Alumni 
 Visitors 
 Students 
 Research 
 ICAM-LANL 
 Quantum 
 Publications 
 Publications 
 2007 
 2006 
 2005 
 2004 
 2003 
 2002 
 2001 
 2000 
 <1999 
 Conferences 
 Workshops 
 Sponsorship 
 Talks 
 Colloquia 
 Colloquia Archive 
 Seminars 
 Postdoc Seminars Archive 
 Quantum Lunch 
 CMS Colloquia 
 Q-Mat Seminars 
 Q-Mat Seminars Archive 
 Archive 
 Kac Lectures 
 Dist. Quant. Lecture 
 Ulam Scholar 
 Colloquia 
 
 Jobs 
 Students 
 Summer Research 
 Student Application 
 Visitors 
 Description 
 Past Visitors 
 Services 
 General 
 PD Travel Request 
 
 History of CNLS 
 
 Maps, Directions 
 CNLS Office 
 T-Division 
 LANL 
 
Thursday, September 13, 2007
2:00 PM - 3:30 PM
CNLS Conference Room (TA-3, Bldg 1690)

Postdoc Seminar

Thermalization and Bottleneck in Turbulence

Jian-Zhou Zhu
T-7

It is conjectured that for many equations of hydrodynamical type (including the 3D Navier--Stokes equations, the Burgers equation and various models of turbulence) the use of hyperviscous dissipation with a high power $\alpha$ (dissipativity) of the Laplacian and suitable rescaling of the hyperviscosity becomes asymptotically equivalent to using a Galerkin truncation with zero dissipation and suppression of all Fourier modes whose wavenumber exceeds a cutoff $k_d$. From recent work of Cichowlas et al (\textit{Phys.\ Rev. Lett.} {\bf 95} (2005) 264502), it is known that when $k_d$ is large enough the solution of Galerkin-truncated equations develop a thermalized range at high wavenumbers (with a $k2$ spectrum in 3D). It is proposed to interpret the phenomenon of bottleneck, which becomes stronger when increasing $\alpha$, as an aborted thermalization. In this first talk, I will discuss the cases of eddy-damped-quasi-normal-Markovian (EDQNM) type models. Artifacts which can appear when using hyperviscosity are also discussed along with the numerical verifications.