Studies on the Wind in the Windward and Leeward of Windbreak Structure
| Autor: | Yushiro Motoda, Seiji Hayakawa |
|---|---|
| Rok vydání: | 1985 |
| Předmět: | |
| Zdroj: | Journal of Agricultural Meteorology. 41:31-38 |
| ISSN: | 1881-0136 0021-8588 |
| DOI: | 10.2480/agrmet.41.31 |
| Popis: | In the present communication, a theoretical analysis of air flow near windbreak structure was carried out to obtain some information about the optimal conditions of structure to be constructed, applying the computor program already proposed (Takahashi, 1982). Two parameters, shelter density (D) and Reynolds number (Re), and a decreasing rate of wind speed, which generally characterize the patterns of air flow, were examined in detail for analysis. The results obtained are summarized as follows:1) The wind flow pattern on both sides of structure varied depending on the values of Re: the decreasing effect of wind speed is maximum in the range of 25 85), the flow pattern clearly depended on flow time as characterized by the following observations. At first, a regular oscillatory motion arose behind windbreak structure and then induced the formation of vortices on both sides of structure. Next, the vortices gradually moved towards downstream and then it was mixed with main flow. The flow finally meandered at a slow or high speed, the weak and strong flows and their appearance regions are characterized according to the change of Re.3) When a simulation model was set using various values of D(=100, 90, 80, 70, 60 and 50%) to see the relationship between D and a reduction of wind flow speed, we found that with lower Re values (Fig. 5) the decreasing rate of wind increased parallel to D value, while in the case of higher Re values (Fig. 6), the D value of 60% was effective for a decrease in flow speed. These phenomena are explained with the formation of vortices or the meandering flow results with the relation between the vortices and main flow.From the data obtained, we conclude that both parameters applied for analysis of air flow are closely related to the wind pattern arising near windbreak structure and offer the optimal conditions for structure. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|