Derivation of subgrid stress tensor pdf documentation is available here. We present a micromechanically motivated form of the curvature energy in infinitesimal isotropic gradient elasticity. These directional interaction terms are matrix-valued allowing to apply the standard orthogonal Cartan Lie-algebra decomposition.
Relations are established to a novel conformally invariant linear Cosserat model. Extensive comparison of published LES models for the unclosed terms emerging in the context of two phase flows. A-priori model analysis dependent on the location relative to the interface. Derivation of two new models, one for scalar flux and one for subgrid stresses. Both models predict the SGS terms with comparable or better accuracy than the alternative closures.
LES of multiphase flow is at an early development stage. Not only turbulent structures but also interfacial deformations need to be captured by SGS models. The fidelity of multiphase LES depends on the complex interaction between turbulence and the phase interface at the unresolved scale. A variety of traditional and more recent SGS models of eddy viscosity or scale similarity type is suggested for the SGS terms in multiphase LES. Two new models for the SGS stress and for the SGS scalar flux are proposed. The first is based on a Taylor series expansion of the convolution filter, the latter is inspired by flamelet theory of turbulent premixed combustion.