著者

坂上 務

出版者

九州大学

雑誌

九州大學農學部學藝雜誌 (ISSN:03686264)

巻号頁・発行日

vol.13, no.1, pp.367-372, 1951-11

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The field experiment were carried out for studying the influence of the windbreak. The windbreak, made by Japan cypresses each about 2 meters high, was built at the central part of the reclained field near the agricultural department of Kyusyu University. The length was 20 meters and its width was about 1 meter. Twenty ane mometers were equipped on the wooden poles in the vicinity of windbreak and the velocities and fluctuations of wind at these points were directly read. The fea ture of wind was traced by smoke as is shown in the photograph. The results observed are concluded as follows: 1) The instantaneous maximum and minimum velocity of wind and its gustiness are quite modified by the existence of windbreak, and there are weak flows of several air masses produced behind the raw. 2) Several weak, large vortexes are appeared leeward of windbreak, and one discontinuous surface is formed between these vortexes and the principal flow of wind, under the surface there is a weak breeze with an opposite direction.模型防風林前後の風速分布は-5Hから20H迄かなり広い範囲迄効き, 之は風速のみならず風の乱れについても云える. それから注意すべきはUMAX/Uが2.3倍にもなり防風林被護地域は瞬間的にはかなり大きな風速も予想されるから防風林効果の論議には平均風速のみでは不十分であると云える. 発煙筒を使用しても以上のことはほぼ確められ, この場合の防風林前後の複雑な気流及びどの辺りに渦流が出来易いかの見込がつけられた.