The logarithms in wall turbulence

Time: Thu 2019-04-25 10.30 - 11.30

Lecturer: Yongyun Hwang (Imperial College)

Location: Faxen, FPL, Teknikringen 8

Abstract. In 1956, A. A. Townsend introduces a theory predicting turbulence intensities in the logarithmic region based on the so-called ‘attached eddy hypothesis’. There is a growing body of evidence that supports this theory, suggesting that the attached eddy hypothesis would be the fundamental theoretical ground for description of wall turbulence at high Reynolds numbers. In this talk, I will present some recent results by our group. First part of the talk will be bifurcation and scaling of exact coherent states in the form of Townsend’s attached eddies. Based on this observation, in the second part, I will introduce a flow model designed to study the dynamics of turbulence related to the attached eddies in their onset. Exact coherent states of this model will subsequently be shown. I will finish this talk with very recent result on the state space of multi-scale turbulence and the relevance of the computed exact coherent states in this case.