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A resolvable subfilter-scale model specific to large-eddy simulation of under-resolved turbulence
 

Summary: A resolvable subfilter-scale model specific to large-eddy simulation
of under-resolved turbulence
Yong Zhou, James G. Brasseur,a)
and Anurag Junejab)
Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park,
Pennsylvania 16802
Received 20 February 2001; accepted 6 June 2001
Large-eddy simulation LES of boundary-layer flows has serious deficiencies near the surface when
a viscous sublayer either does not exist rough walls or is not practical to resolve high Reynolds
numbers . In previous work, we have shown that the near-surface errors arise from the poor
performance of algebraic subfilter-scale SFS models at the first several grid levels, where integral
scales are necessarily under-resolved and the turbulence is highly anisotropic. In under-resolved
turbulence, eddy viscosity and similarity SFS models create a spurious feedback loop between
predicted resolved-scale RS velocity and modeled SFS acceleration, and are unable to
simultaneously capture SFS acceleration and RS­SFS energy flux. To break the spurious coupling
in a dynamically meaningful manner, we introduce a new modeling strategy in which the
grid-resolved subfilter velocity is estimated from a separate dynamical equation containing the
essential inertial interactions between SFS and RS velocity. This resolved SFS RSFS velocity is
then used as a surrogate for the complete SFS velocity in the SFS stress tensor. We test the RSFS
model by comparing LES of highly under-resolved anisotropic buoyancy-generated homogeneous

  

Source: Ahlers, Guenter - Department of Physics, University of California at Santa Barbara

 

Collections: Physics