title: Scaling of near-wall flows in quasi-two-dimensional turbulent channels.
abstract: The law of the wall and the log law rule the near-wall mean velocity profile of three-dimensional turbulent flows. These well-known laws, which are validated by legions of experiments and simulations, may be universal. Here, using a soap-film channel, we report the first experimental test of these laws in quasi-two-dimensional turbulent channel flows under two disparate turbulent spectra. We find that despite the differences with three-dimensional flows, the laws prevail, albeit with notable distinctions: the two parameters of the log law are markedly distinct from their three-dimensional counterpart; further, one parameter (the von Kármán constant) is independent of the spectrum whereas the other (the offset of the log law) depends on the spectrum. Our results suggest that the classical theory of scaling in wall-bounded turbulence is incomplete wherein a key missing element is the link with the turbulent spectrum.
authors: Okinawa Institute of Science and Technology, Okinawa, Japan 904-0495.
authors: D
authors: D
authors: Samanta
authors: University of Bordeaux, LOMA (UMR 5798 CNRS), 351 cours de la Libération, 33405 Talence, France.
authors: F
authors: F
authors: Ingremeau
authors: Okinawa Institute of Science and Technology, Okinawa, Japan 904-0495 and Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors: R
authors: R
authors: Cerbus
authors: Division of Thermal and Fluids Engineering, School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore.
authors: T
authors: T
authors: Tran
authors: Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors: W I
authors: WI
authors: Goldburg
authors: Okinawa Institute of Science and Technology, Okinawa, Japan 904-0495.
authors: P
authors: P
authors: Chakraborty
authors: University of Bordeaux, LOMA (UMR 5798 CNRS), 351 cours de la Libération, 33405 Talence, France.
authors: H
authors: H
authors: Kellay