Wed March 2nd 2011
Seminar Macroscopic effects of the spectral structure in turbulent flows
Tuan Tran


There is a missing link between the macroscopic properties of turbulent flows, such as the frictional drag of a wall-bounded flow, and the turbulent spectrum. The turbulent spectrum is a power law of exponent α (the ʽspectral exponentʼ) that gives the characteristic velocity of a turbulent fluctuation (or ʽeddyʼ) of size s as a function of s. Here we seek the missing link by comparing the frictional drag in soap-film flows, where α=3, and in pipe flows, where α=5/3. For moderate values of the Reynolds number Re, we find experimentally that in soap-film flows the frictional drag scales as Re-1/2, whereas in pipe flows the frictional drag scales as Re-1/4.
Each of these scalings may be predicted from the attendant value of α by using a new theory, in which the frictional drag is explicitly linked to the turbulent spectrum.
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The 10th Complex Motion in Fluids 2021
Max Planck Gesellschaft
Centre for Scientific Computing