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Intermediate Scaling and the Outer Peak for Streamwise Velocity in Wall Turbulence

Tid: To 2022-06-09 kl 10.30 - 11.30

Plats: Faxén, Teknikringen 8

Föreläsare: Jonathan Morrison (Imperial College London)

We will review intermediate scaling for the mean velocity and variance of the streamwise velocity in pipe flow and boundary layers, based on the wall-normal position at which the streamwise variance is a maximum, y_m. The key insight is that separation of scales in the two-layer model is proportional to (Re_\tau)^{1/2} explaining the slow approach to asymptotic conditions and the appearance of log laws for Re_\tau > 20,000. To explain the choice of intermediate scales, we investigate the emergence of the outer peak of the variance which roughly coincides with the appearance of the log laws. Noting that the outer peak appears in the local-equilibrium region, we can make estimates of the non dimensional dissipation rate which also increases in proportion to (Re_\tau)^{1/2}.

Innehållsansvarig:Ardeshir Hanifi
Tillhör: FLOW
Senast ändrad: 2022-05-20