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Dynamic Subgrid Scale Modeling of Turbulent Flows using Lattice-Boltzmann Method | Kannan N. Premnath
; Martin J. Pattison
; Sanjoy Banerjee
; | Date: |
6 Jan 2009 | Abstract: | In this paper, we discuss the incorporation of dynamic subgrid scale (SGS)
models in the lattice-Boltzmann method (LBM) for large-eddy simulation (LES) of
turbulent flows. The use of a dynamic procedure, which involves sampling or
test-filtering of super-grid turbulence dynamics and subsequent use of
scale-invariance for two levels, circumvents the need for empiricism in
determining the magnitude of the model coefficient of the SGS models. We employ
the multiple relaxation times (MRT) formulation of LBM with a forcing term for
simulation of the grid-filtered dynamics of large-eddies. The dynamic procedure
is illustrated for use with the common Smagorinsky eddy-viscosity SGS model. We
also discuss proper sampling techniques or test-filters that facilitate
implementation of dynamic models in the LBM. For accommodating variable
resolutions, we employ locally refined grids in this framework. As examples, we
consider the canonical fully developed turbulent channel flow at two different
shear Reynolds numbers $Re_{*}$ of 180 and 395. The approach is able to
automatically and self-consistently compute the values of the Smagorinsky
coefficient, $C_S$. In particular, the computed value in the outer or bulk flow
region, where turbulence is generally more isotropic, is about 0.155 (or the
model coefficient $C=C_S^2=0.024$) which is in good agreement with prior data.
The model coefficient is also found to become smaller and approaches towards
zero near walls, reflecting the dampening of turbulent length scales near walls
and the computed turbulence statistics are also in good agreement with prior
data. The paper also discusses a procedure for incorporation of more general
scale-similarity based SGS stress models. | Source: | arXiv, 0901.0593 | Services: | Forum | Review | PDF | Favorites |
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