Kinetic energy dissipation by
subgrid-scale stresses in turbulent flows

Charles Meneveau, Johns
Hopkins University

One of the most important features of unresolved small scales
in Large-Eddy-Simulation is the rate at which they extract kinetic energy
from the resolved flow. We examine an experimental surrogate of the subgrid
(SGS) dissipation rate, by means of high Reynolds number experimental data
in the cylinder wake. Mean profiles are measured and compared *a priori*
with several models (Smagorinsky, similarity model, dynamic Smagorinsky).
More detailed comparisons are achieved by means of conditional averaging,
both with outer intermittency and with the phase of coherent structures
(Karman vortices) in the near wake. The results provide evidence that learning
from resolved scales (such as in the dynamic and similarity models) leads to more
realistic predictions than the constant-coefficient eddy-viscosity model, when
turbulence is spatially complex and when coherent structures affect the SGS
dynamics directly.

**References**

J. O'Neil and C. Meneveau 1997, "Subgrid-scale stresses and their modelling in a turbulent plane wake," J. Fluid Mech. 349, p. 253-293.

S. Liu, C. Meneveau and J. Katz 1994, "On properties of similarity subgrid-scale models as deduced from measurements in a turbulent jet," J. Fluid Mech. 275, p. 83.

C. Meneveau 1994, "Statistics of turbulence subgrid-scale stresses: Necessary conditions and experimental tests," Phys. Fluids A 6, p. 815.

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