[NotiAMCA] Seminario en el CSC
sonzogni en intec.unl.edu.ar
Lun Nov 3 19:04:28 ART 2014
En el Centro de Simulación Computacional de CONICET, el próximo jueves 13 a las 11hs tendremos el siguiente seminario:
SPECTRA AND MEAN-VELOCITY PROFILES IN TURBULENT PIPE FLOW
Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
Two aspects of turbulent pipe flow have been the subject of extensive, disjunct research efforts: average properties like the frictional drag and the mean-velocity profile (MVP), and the energy spectrum of the turbulent fluctuations. In this talk we seek to establish a link between the MVP of a turbulent pipe flow and the energy spectrum of the turbulent fluctuations in the flow. The idea is to use this hitherto missing ``spectral link'' to help us shed new light on the MVP by building on the well-known structure of the energy spectrum. We start with a brief review of the energy spectrum. Next, we carry out a spectral analysis to identify the eddies that dominate the production of shear stress via momentum transfer. This analysis allows us to express the MVP as a functional of the spectrum. Each layer in the MVP turns out to be related to a specific spectral range: the buffer layer to the dissipative range, the log layer to the inertial range, and the wake to the energetic range. The parameters of the spectrum set the thickness of the viscous layer, the amplitude of the buffer layer, and the amplitude of the wake. Our findings verify the longstanding conjecture that in wall-bounded turbulent flows there is a close relation between spatial structure and spectral structure. I will try to explain all salient concepts from scratch; even if you are innocent of any fluid mechanics, I guarantee you will learn something! This research was carried out in collaboration with Pinaki Chakraborty, Nigel Goldenfeld and Nicholas Guttenberg.
Eduardo N. Dvorkin
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