Wavelet Analysis of Vortex Tubes in Experimental Turbulence.pdf

Wavelet Analysis of Vortex Tubes in Experimental Turbulence Hideaki Mouri 1 Meteorological Research Institute, Nagamine 1-1, Tsukuba 305-0052, Japan 0 0 2 v Masanori Takaoka o N Department of Mechanical Engineering, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan 3 1 (February 9, 2008) ] n y d - Abstract u l f . s This report proposes a new method to study vortex tubes in one-dimensional c i s velocity data of experimental turbulence. Vortex tubes are detected as local y h p maxima on the scale-space plot of wavelet transforms of the velocity data. [ 1 Then it is possible to extract a typical velocity pattern. The result for data v 7 obtained in a wind tunnel is consistent with those of three-dimensional direct 0 1 numerical simulations. 1 1 PACS numbers: 47.27.Gs, 07.05.Kf 1 0 / s c i s y h p : v i X r a Typeset using REVT X E 1 By using direct numerical simulations and bubble/cavitation experiments, it has been established that turbulence contains vortex tubes [1–4]. Regions of intense vorticity are or- ganized into tubes. Their radii and lengths are, respectively, of the orders of the Kolmogorov length η and the integral length L. Vortex tubes occupy a small fraction of the volume and are embedded in a background flow, which is random and of large scales. Especially when the Reynolds number Reλ is high, effects of vortex tubes on the velocity field are of interest [4]. The veloci