Dimension Reduction in Turbulence--the Navier-Stokes Alpha Model



DARRYL HOLM
Theoretical Division and CNLS
Los Alamos National Laboratory, MS B284
Los Alamos, NM 87545, USA

http://cnls.lanl.gov/~dholm/
dholm@lanl.gov



Abstract:  The Navier-Stokes-alpha equations model the effects of subgrid scale fluctuations in fluid turbulence as nonlinear dispersion. (This nonlinear dispersion smooths the transport velocity of the fluid loop in Kelvin's circulation theorem for the alpha model, relative to the circulation velocity in its integrand.) Holm will review the theoretical and physical framework for deriving these equations, the comparison of their steady solutions to experimental mean velocity profiles for turbulence in channels and pipes at high Reynolds numbers, and the analytic and computational studies that illustrate their effectiveness as a fluid turbulence model with a reduced number of degrees of freedom.



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