2026-09-21T04:09:11Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/34359 2023-07-10 col_2142_5131 col_2142_14787 com_2142_5130 com_2142_9630 com_2142_234

Gioia, Gustavo Gioia, Gustavo Chrakraborty, Pinaki Christensen, Kenneth T. Freund, Jonathan B. Zuniga Zamalloa, Carlo 2012-09-18T21:13:12Z 2012-09-18T21:13:12Z 2012-08 2012-09-18T21:13:12Z 2012-08 Motivated by a recently proposed theory that entails the existence of a “spectral link” between the turbulent energy spectra and the attendant turbulent mean velocity profile in a pipe flow, we establish new scaling laws for the turbulent energy spectra of pipe flows. These new scaling laws— an inner scaling law and an outer scaling law—differ from the scaling laws that were predicated on Townsend’s attached–eddy hypothesis in that they are proper analogues (or spectral counterparts) of the classical scaling properties of the turbulent mean velocity profile. To test the new scaling laws, we have recourse to (1) published computational data from direct numerical simulations and (2) new experimental data from unprecedented measurements, carried out in our laboratory, of the streamwise component of the turbulent energy spectrum on numerous locations along the radii of three rough-walled pipes, for flows spanning a decade in Reynolds number. We show that the new scaling laws are consistent with the turbulent energy spectra of both smooth– and rough– walled flows. In addition, we use the new experimental data to probe the spatial distribution of the streamwise turbulent kinetic energy u2 , the longitudinal integral length scale L11 , and the Kolmogorov length scale η in turbulent rough–walled pipe flows. We document in our rough– pipe flows a striking phenomenon recently discovered in smooth–pipe flows: the occurrence of an outer peak in u+2 (y + ), whose magnitude is an increasing function of the Reynolds number, but the Reynolds number where the outer peak emerges is an order of magnitude smaller than the corresponding Reynolds number in smooth pipes. Last, we carry out a comparative study of the three canonical wall–bounded turbulent flows: pipe flow, channel flow, and boundary layer flow. We are able to trace the similarities and disparities among the turbulent mean velocity profiles of the three canonical flows to corresponding similarities and disparities among the attendant turbulent energy spectra—new evidence of the existence of a spectral link between the turbulent mean-velocity profile and the turbulent energy spectra. Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2012-06-21T21:00:30Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 1 Zuniga-Zamalloa_Carlo.pdf: 11622751 bytes, checksum: 06c2d291ad0f21d1c4d1ed9b525fe904 (MD5) Made available in DSpace on 2012-09-18T21:13:12Z (GMT). No. of bitstreams: 2 Zuniga-Zamalloa_Carlo.pdf: 11622751 bytes, checksum: 06c2d291ad0f21d1c4d1ed9b525fe904 (MD5) license.txt: 4062 bytes, checksum: b12ee8f289148fbce114201ef5f53ec5 (MD5) http://hdl.handle.net/2142/34359 en Copyright 2012 Carlo Zuniga Zamalloa turbulence rough pipe energy spectra hotwire friction factor Experiments on turbulent flows in rough pipes: spectral scaling laws and the spectral link Mechanical Sci & Engineering 1917 Theoretical & Applied Mechans 0242 University of Illinois at Urbana-Champaign Dissertation Ph.D. PHD:Theor&Appl Mechanics -UIUC 10KS0242PHD