Realizable Dynamic Large Eddy Simulation
A very attractive feature of large eddy simulation (LES) is the possibility to apply the dynamic subgrid scale model calculation developed by Germano et al. Phys. Fluids A 3:1760–1765, 1991, . This is a method for the calculation of model parameters as functions of time and space as the simulation progresses. It avoids empirical treatment of model parameters such as damping or wall modeling near the wall boundaries. On the other hand, dynamic LES models usually suffer from instabilities. The mechanism of instability of dynamic sub-grid scale (SGS) models has not yet been fully clarified. Several methods are in use for the stabilization of dynamic SGS models. The most popular methods are clipping of model parameters and their space averaging in homogeneous directions. These stabilization techniques are often difficult or even impossible to apply. In real flows, there are no homogeneous directions in space. It is also difficult to find appropriate clipping values for dynamic LES parameters, which can depend on the type of flow, Reynolds number and grid resolution.
The authors would like to acknowledge support through NASA’s NRA research opportunities in aeronautics program (Grant No. NNX12AJ71A) and support from the National Science Foundation (DMS-CDS&E-MSS, Grant No. 1622488). We are very thankful for computational resources provided by the Wyoming Advanced Research Computing Center  and the Wyoming-NCAR Alliance .
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