Computational Models of the Viscous Sublayer and Limiting Behavior of Turbulence Near a Wall.

Three computational models of incompressible viscous sublayer turbulence have been developed using the time-dependent Navier-Stokes equations with prescribed velocity boundary conditions at the outer edge of the sublayer. The models attempt in different ways to simulate the highly elongate, quasi-periodic, coherent structures observed experimentally. Comparison of computed results with experiment is good for mean streamwise velocity, mean Reynolds stress, and correlation coefficient and reasonably good for the three turbulence intensities, skewness and flatness of streamwise velocity and of Reynolds stress. Within a thin layer adjacent to the outer edge, all three models yield anomalously high values for dissipation and streamwise vorticity intensity. Computations using a fine mesh establish the limiting behavior of turbulence quantities very near a wall. Below about 0.3 wall units, the variations with distance from the wall were found to be linear for streamwise turbulence, spanwise turbulence, and departure of dissipation and streamwise vorticity from their wall values second power for turbulence normal to the wall third power for Reynolds stress and a constant non-zero value for the correlation coefficient.