Tests of Subgrid-Scale Models in Strained Turbulence. Studies of the Structure of Homogeneous Shear Flows. Developing a Model of Turbulence Near a Wall from Solutions of the Navier-Stokes Equations.

摘要

Three studies are described, each of which makes use of turbulent flow fields calculated using the Navier-Stokes equations. In the first study, exact numerical solutions of the full Navier-Stokes equations are used to evaluate subgrid-scale models used in large-eddy simulations. The flows investigated are homogeneous and incompressible with strong imposed mean strain or shear. Models evaluated include the conventional Smagorinsky model as well as a recently introduced formulation based on the notion of scale similarity. In the second study, exact numberical simulations of homogeneous shear flows are examined using various computer-graphic tools, the aim being to attempt to understand the mechanisms underlying the production of turbulence energy and growth of length scales in such flows. The subject of the third study is the development of a computational model of the viscous sublayer of wall-bounded incompressible turbulent flow. In this work, the time-dependent Navier-Stokes equations, suitably simplified, are solved subject to boundary conditions imposed at the outer edge of the viscous sublayer. The formulation of these edge conditions so that computed average distributions of turbulence quantities agree with experimental data through the sublayer is the essence of work.