Journal of Spatial Analysis

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Proper design of the central courtyard in residential areas against Sadobist-roz-e winds in Zabol using CFD analysis
Saeide Khaksefidi - Ma Student of Architecture, Faculty of Architecture and urban planning, Jundi-shapur University of technology, Dezful, Iran.
Behzad Vasigh* - Faculty of Architecture and Urban planning, Jundi-shapur University of Technology, Dezful, Iran
Mohsen Taban - Assistant Professor, Faculty of Architecture and urban planning, Jundi-shapur University of Technology, Dezful, Iran
Abstract:
Wind erosion occurs in many arid, semiarid and agricultural areas of the world. Sadobist-roz-e winds are common phenomena in arid and semi-arid areas. In recent years, Sadobist-roz-e winds frequencies and intensities have increased significantly in Iran. A research on Sadobist-roz-e winds sources is important for understanding the mechanisms of dust generation and assessing its socio-economic and environmental impacts. Deserts are the main sources of emitted dust, and are highly responsive to wind erosion. Low content of soil moisture and lack of vegetation cover lead to fine particle’s release. The wind in the eastern part of Iran, Sistan, is one of the most important phenomena in the ecological studies. The intensity and velocity of the wind, has caused environmental problems. This population is distributed in more than 1000 cities, villages and nomadic settlements. Sadobist-roz-e winds is the most significant wind in the region which starts every year at the end of the spring and lasts all through the beginning of autumn, with a mean velocity of 100 km/h. Architecture and urbanization of the Sistan region have been built with the focus on reducing the amount of sand. The orientation and placement of buildings can be effective in reducing the damage to these winds. Sadobist-roz-e winds has increased in zabol since 1999. The average annual number of dust Storm events increased from 10 d during 1990–1998 (before the drought) to 54 d during 1999–2004 (after the drought). The frequency of dust storms also increased 5-fold after 1999 in the region. This shift is associated with an increase in wind speed, rainfall reduction, drying of Hamoun Lake and drought occurrence. The purpose of this paper is to determine the type of obstruction, orientation and enclosure level of the central courtyard so that it can be useful in two areas: wind speed reduction and reduction of dust contamination in the building area. Modeling of buildings is done using 3D software; and simulation of airflow using “Flow3D” Fluid Simulation software has been investigated.  Each time the flow of air was tested in different models. First, two main patterns that were expected to be appropriate to the behavior of the wind were selected. Both of them were simulated and it was found that the concave shape has a better performance. Because in addition to reducing the wind speed, it also causes rotational movement. Then, with emphasis on the central courtyard, various shapes of the layout of the builders in the central courtyard were examined. The result showed that due to the high initial wind speed, in addition to the inflow and outflow contours (in the enclosure court), the positioning and orientation of buildings at different angles, it can also be effective in reducing wind speed and decreasing wind movement. By extending this collection to more buildings and creating congestion conditions, the comfort conditions for the pedestrian were examined. In the following, with a constant elevation of 9, and enclosure (H / D ratio) and wind input to a set of 3, this load was simulated with different angles against the wind. Every time the wind speed and the wind velocity decreases. The best location was selected at a 45-degree angle faced to the wind. Further, with regard to the fact that high wind speeds are observed in the best building layout, natural obstacles were used to reduce wind speed. Among the native trees of Sistan, “Gaz” were selected because of their highest adaptability to the region's climate and for research purposes. Physical characteristics were taken and modeling was done. Each simulation was performed; the best model with a natural barrier against the wind region was identified. Although the research on locality could be highly generalized, the best location in the study, which was close to the definitions, was approached. At last, the results show that buildings or obstacles that are concave to the wind direction are more likely to prevent wind entering the shadows area than most other building types. The type of layout and orientation of the buildings against the wind and the amount of enclosure at the two points of “entry and exit of the wind”, along with the use of natural obstacles, can be very effective in reducing the wind speed and reducing the entry of dust to the comfort level.
 
Keywords: zabol, sadobistroze winds, CFD simulation, Residential complex, central courtyard