再層流化過程のポアズイユ流における乱流構造の維持機構(境界層・せん断流・遷移(1),一般講演)

概要

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The direct numerical simulations (DNSs) with a spectral method are performed to study sustain mechanism of turbulent structure in relaminarizing Poiseuille flow where quasi-laminar and turbulent regions simultaneously appear in the computational region. In quasi-laminar region, streamwise vortical structure disappears and very long low-speed streaks appear, while in the turbulent region, many quasi-streamwise vortices exist densely. The criterion using streamwise vorticity is found to be useful to distinguish between quasi-laminar and turbulent regions. The advection velocity of the turbulent and laminar regions is 14.2 which is slightly larger than balk mean velocity. Turbulent kinetic energy is transferred from turbulent to quasi-laminar region in the region away from the wall, while it is transferred vise versa in very near wall region. This energy transfer, mainly driven by low and high speed streaks, contributes to keeping turbulent and quasi-laminar regions steady.
日本流体力学会の論文
2008-09-04