著者

三宅 裕 藤井 貴広 范 秦寅

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. B編 (ISSN:03875016)

巻号頁・発行日

vol.73, no.729, pp.1167-1174, 2007-05-25

被引用文献数

2

---

A model for an irregularly indented rough surface has been proposed by the authors in which tall peaks are picked up and represented by hemispheres having equal volume to corresponding peak. In practical application, drag of a hemisphere is substituted by plane shear stress on a flat plate. This simplified model surface is used to simulate flow over the original rough surface. The model requires drag of a hemisphere on a flat plate. In this work, unique drag formula which is simple and acceptably accurate in balance with the compactness of the model, is investigated by numerical simulations. The formula for a hemisphere on a flat plate is deduced on the basis of simulations by RANS, of channel flows having periodically arranged hemispheres on both plates. Obtained formula is confirmed to compare reasonably to those realized by hemispheres of different size in different ambient situation, in a rough wall channel flow, though drag largely scatters. The form is applied also to pipe flows having periodic hemispheres on the wall and is found to reproduce measured friction, satisfactorily. Although the proposed idea must be examined farther carfully and should be improved in details, promising step has been set up to make proposed model a useful method in practical application.