放射状膜流れに関する研究 : 第5報,乱流遷移に及ぼす壁面粗さの影響

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This paper discribes the influence of wall roughness on the transition from laminar to turbulent flow occurred in the redial flow of a thin liquid film. Visual observations on the properties of liquid surface were performed on the plates with the following three types of distributed roughness; (a) saw-toothed roughness and (b) trapezoidal shaped roughness, both of which were regularly constructed in a concentric configuration, and (c) irregularly distributed sand roughness. It was found that the point of transition moved upstream as the height of wall roughness in creases under otherwise identical conditions, and that the transition occurred in each of the three regions of flow, namely, (1) the stagnation flow, (2) the region in which the laminar boundary layer grows, and (3) the region in which the whole flow is the laminar boundary layer. Furthermore, experimental results showed that the critical local Reynolds number decreases according as the height of wall roughness increased.
1984-12-25