| Fri September 5th 2014 15:00 – 16:00 ZH286 | Seminar | Log laws in wall-bounded turbulent flows Lex Smits |
Details:Logarithmic scaling is one of the corner stones of our understanding of wall-bounded turbulent flows. In 1938, Clark B. Millikan advanced an overlap argument that framed the logarithmic variation of the mean velocity in simple dimensional terms. Seventy-five years later, however, basic aspects of this logarithmic region, such as its slope (described by von Karman’s constant), and its spatial extent, are still being debated. In addition, Townsend in 1976 proposed a logarithmic scaling for the streamwise and spanwise components of turbulence based on the attached eddy hypothesis, and Perry and Abell in 1975 suggested a similar scaling based on a spectral overlap argument. Until recently, the experimental verification had been elusive. Here, we use pipe and boundary layer flow measurements over a very large Reynolds number range to examine these expectations of logarithmic scaling, and to show that at sufficiently high Reynolds number these flows reveal both expected and unexpected implications for our understanding and our capacity to model turbulence. | ||
