壁面粗さを有するチャネル流の安定性に関する数値実験

The effect of beginning of roughness patch on the evolution of two-dimensional Tollmien-Schlichting waves is investigated theoretically and numerically. The wall roughness is found to destabilize the flow through the positive energy production just above the inflection point of base flow in the concave region of the roughness. For the change in wall geometry, about 14 periods are needed to attain the stability characteristic of streamwise-periodically corrugated roughness when the wavelength of the T-S wave and wall corrugation is comparable while the effect of change in average position of roughness remains further. The latter influence is also studied by considering channel with a simple expansion/contraction. It is shown that evolution of base flow towards the plane Poiseuille flow downstream of step is found to be represented by using slowly-decaying stationary eigenmodes, similar to that for the channel entrance flow. It is also found that the influence of sudden expansion/contraction to the stability of flow persists far downstream.
Meeting Information: 43rd JAXA Workshops on "Investigation and Control of Boundar-Layer Transition" (October 2-3, 2008) ; 44th JAXA Workshops on "Investigation and Control of Boundar-Layer Transition" (March 26-27, 2009)
会議: 第43回（2008年10月2日-10月3日）「境界層遷移の解明と制御」研究会; 第44回（2009年3月26日-3月27日）「境界層遷移の解明と制御」研究会