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Turbulence closure

One of the main challenges in LES modeling is the turbulence closure. The filtering process yields four SGS covariance terms (see Eqs.~\ref{eq:nse}\ref{eq:1hss}) that cannot be explicitly calculated. In PALM, these SGS terms are parametrized using a 1.5-order closure after Deardorff (1980). PALM uses the modified version of Moeng and Wyngaard (1988) and Saiki et al. (2000). The closure is based on the assumption that the energy transport by SGS eddies is proportional to the local gradients of the mean quantities and reads

References

• Deardorff JW. 1980. Stratocumulus-capped mixed layers derived from a three-dimensional model. Bound.-Lay. Meteorol. 18: 495–527.

• Moeng CH, Wyngaard JC. 1988. Spectral analysis of large-eddy simulations of the convective boundary layer. J. Atmos. Sci. 45: 3573–3587.

• Saiki EM, Moeng CH, Sullivan PP. 2000. Large-eddy simulation of the stably stratified planetary boundary layer. Bound.-Lay. Meteorol. 95: 1–30.