Keisuke Fukui

Forming Process of Organized Turbulent Structure in Unstably and Combined Density-Stratified Turbulent Flow.

平行平板間における不安定および共存密度成層乱流場の発達過程に関して, 温度変動による条件付きサンプリング法により, 組織的乱流構造の形成過程を調べた.不安定成層乱流場では, 加熱された下面近傍で発生した小さな組織渦が下流に行くにつれて上壁面にまで達する大規模乱流縦渦に発達することがわかった.共存密度成層乱流場では, 密度成層の発達に伴い, 不安定成層内部で生じた上昇流が安定成層内部にまで到達し乱流縦渦を形成するが, 上部の安定成層の影響で横方向に流れを生じ, 形の歪んだ乱流縦渦が形成されることが明らかになった.また, 共存密度成層乱流場では, 乱流縦渦の成長に伴って上層部と下層部に, それぞれ薄い層の組織的構造が発達することを明らかにした.

Process of Forming a Turbulent Thermal Plume in a Density-Stratified Turbulent Flow between Parallel Flat Plates.

Processes of forming an organized turbulent thermal plume are investigated in unstable stratified and in combined stably and unstably stratified turbulent flows between parallel flat plates by conditional sampling measurement, in which temperature fluctuation near the wall is used as the detecting signal. The turbulent thermal plume is found to form in an unstable region of both combined and unstable stratified flows. The width of turbulent thermal plume increases downstream in developing unstablystratified turbulent flow. In combined stratified flow, however, development of the thermal plume is suppressed because the stably stratified flow existed over the unstable flow.