Mesoscale modeling for turbulence based on EMMS principle
Abstract
Turbulent flows in engineering are characterized by the coexistence of turbulent and non-turbulent fluids. Nonetheless, in traditional turbulence models, the laminar portion of the fluid flow is often neglected and constitutive laws are expressed to describe fully turbulent states within computational grids. This situation is perceived as a source of inaccuracies in modeling practical engineering flows. In this paper, a meso-scale turbulence model based on the principle of energy-minimization multi-scale model (EMMS) for improving the accuracy of turbulence modeling is presented. Then, the multi-scale structure and stability criterion originated from the compromise in competition between viscous and inertial control coordination mechanisms in turbulent flows are explored, and the physical basis of the model's extension, the mathematical expression, the verification and the application are also analyzed. Furthermore, the contradiction between the hypothesis of minimum energy dissipation rate and that of maximum energy dissipation rate in hydraulics can be interpreted in a unified framework of the EMMS-based turbulence model. Finally, some problems and challenges in the EMMS-based turbulence model and the development of the turbulence-based meso-sciences are also discussed.
