Modeling of energy backscatter via an algebraic subgrid-stress model

In large-eddy simulation, the subgrid-stress model is included to represent the energy-transfer mechanisms between the resolved and unresolved scales of motion. Although most models represent forward scatter (dissipation) of energy, they fail to account for backscatter properly. The algebraic model, obtained directly from the closure of the subgrid stresses, has an additional term over the mixed model that accounts for the backscatter of energy explicitly. This model has been previously documented in the open literature and shows promising results in accounting for the subgrid-scale energy-transfer mechanisms. Detailed documentation is provided of the backscatter capability of the algebraic model, for a series of test cases including isotropic turbulence, plane channel flow, and two free shear flows. The model performace in predicting turbulent Now quantities is also compared with commonly used subgrid-stress models and with the available direct-numerical-simulation data.