円管内乱流パフの構造(乱流基礎(5),一般講演)

概要

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A turbulent puff is realized in a straight circular pipe flow driven by a constant uniform force. The direct numerical simulation of the Navier-Stokes equation for an incompressible viscous fluid is performed with periodic boudary condition in the axial direction with period 16π pipe radius. The Reynolds number is 3000 based on the pipe radius and the centerline velocity of the Hagen-Poiseuille flow corresponding to the imposed external force. The puff moves downstream with the mean axial flow velocity, hardly changing the axial extent, thus called an equilibrium puff. The flow is turbulent in the puff with a number of low-speed streaks along the pipe wall. It is found that the equilibrium puff is sustained by continuously supplied excitation at the trailing edge by the roll-ups of those vortex layers that are created between the low-speed streaks moving up from the turbulent puff and the laminar flow coming down from upstream.
日本流体力学会の論文
2008-09-04