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In order to understand the effects of the wall permeability on turbulence near permeable walls, spanwise flow field mea- surements are carried out for turbulent flows in channels with permeable bottom walls by a two-component particle velocimetry (PIV) system. The porous media used are three kinds of foamed ceramics which have almost the same porosity (∼ 0.8) but different perme- ability. The turbulent flow fields in the spanwise planes are discussed using instantaneous and statistical measurement data. At a small permeability Re (ReK ), low speed and high speed regions, which form a similar streaky structure to that of solid-wall turbulence, are observed. In case of a large ReK , although some large scale striped patterns are observed, they are confirmed to be different from those of the solid wall turbulence structure.
Author(s):
Yuka Nakagawa
Osaka Prefecture University
Japan
Masayuki Kaneda
Osaka Prefecture University
Japan
Kazuhiko Suga
Osaka Prefecture University
Japan