On the Hydraulic Resistance of Two Dimensional Roughness

二次元粗度の流体抵抗について

On the Hydraulic Resistance of Two Dimensional Roughness

Creators Tsubaki Toichiro

Synopsis. As the foundamental cases of two dimensional roughness, we have discussed the flow characteristics of stream over the rectangular roughness and of the cylinderical roughness placed transversely to the direction of flow. Taking into account the properties of wake created by the roughness, the flow pattern within the roughness layor and the hydrodynamical forces acting on the battens themselves are estimated. As the results, it is pointed out that the occurrence of the maximum of the equivalent roughness at the spaceing-height ratio of 9?18,which has been well known experimentally with no satisfactory theory, is attributed to the fact that the shape resistance per one roughness increases with increase of spaceing-height ratio, while the number of roughness per unit length decreases conversely. The theoretical results are verified with the experimental results summarised by J. W. Johnson for rectangular roughness and with those by Hosoi for cylinderical roughness.

[NCID]AN00244217