The application of large-eddy simulation (LES)
to particle-laden turbulence raises such a fundamental question
as whether the LES with a subgrid scale (SGS) model can
correctly predict Lagrangian time correlations (LTCs). Most
of the currently existing SGS models are constructed based
on the energy budget equations. Therefore, they are able to
correctly predict energy spectra, but they may not ensure the
correct prediction on the LTCs. Previous researches investigated
the effect of the SGS modeling on the Eulerian time
correlations. This paper is devoted to study the LTCs in LES.
A direct numerical simulation (DNS) and the LES with a
spectral eddy viscosity model are performed for isotropic
turbulence and the LTCs are calculated using the passive
vector method. Both a priori and a posteriori tests are carried
out. It is observed that the subgrid-scale contributions to
the LTCs cannot be simply ignored and the LES overpredicts
the LTCs than the DNS. It is concluded from the straining
hypothesis that an accurate prediction of enstrophy spectra
is most critical to the prediction of the LTCs.
; He GW(何国威)
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