多孔質壁を有する円管内乱流の乱流特性

抄録

We report on the experiments of turbulent pipe flow with a porous wall. The pipe wall consists of a cylindrical porous medium in which there are many radial fine through-holes connected with a plenum chamber. We have investigated the dependence of friction factor f on Reynolds number Re up to Re~10⁵ in porous pipe flow with a chamber, porous pipe flow without a chamber, and a smooth pipe flow. In the non-porous case, turbulent flow exhibits the Blasius law f = 0.3164Re^-1/4 in the range of 3 × 10³ ≲ Re ≲ 10⁵. In porous pipe flow with chamber, on the other hand, we have found the scaling f~Re⁰ at higher Re ≳ 2 × 10⁴, implying the Taylor dissipation law. In porous pipe flow without chamber, the friction drag increases compared to the non-porous case, but f decreases with increasing Re at Re ≲ 10⁵. The significant difference in porous pipe flows with and without chamber suggests that the scaling f~Re⁰ in porous pipe flow with chamber is attributed to the fluid motion through the porous wall.