Abstract
Composite sweeping-enhanced resolvents, referred to as the
${\boldsymbol {R}}_s^2$
model, are proposed to predict the space–time statistics of large-scale structures in turbulent channel flows. This model incorporates two key mechanisms: (i) eddy damping is introduced to represent random sweeping decorrelation caused by nonlinear forcing, leading to a sweeping-enhanced resolvent
${{\boldsymbol {R}}_s}$
; and (ii) the sweeping-enhanced resolvent
${{\boldsymbol {R}}_s}$
is composited into its iterations
${\boldsymbol {R}}_s^2$
to yield non-zero Taylor time microscales. The resulting
${\boldsymbol {R}}_s^2$
model can correctly predict the frequency spectra and two-point cross-spectra of large-scale structures. This model is compared numerically with eddy-viscosity-enhanced resolvent models. The latter are designed to represent energy transfer instead for time decorrelation, and thus underpredict the characteristic decay time scales. The
${\boldsymbol {R}}_s^2$
model correctly yields the characteristic decay time scales in turbulent channel flows.
Funder
National Natural Science Foundation of China
China Postdoctoral Science Foundation
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics,Applied Mathematics
Cited by
7 articles.
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