طراحي بهينه ي حياط مركزي در ساختمان هاي مسكوني در برابر باد 120روزه زابل براساس تحليل CFD

Proper design of the central courtyard in residential areas against Sadobist-roz-e winds in Zabol using CFD analysis

منطقه­ زابل يكي از مناطق باد­خيز شرق ايران است. كيفيت، شدت و سرعت زياد بادهاي اين منطقه موسوم به بادهاي 120 روزه سيستان عامل بروز مشكلات فراوان زيست محيطي و اجتماعي ­است. اين بادها نقش موثري در حمل ماسه­ هاي كويري ايفا مي ­كنند و تجربه تاريخي معماري و شهرسازي اين منطقه معطوف به مقابله با اثرات مخرب پراكنش ماسه است. يكي از اين گزينه ها ­جهت­ گيري­­ و قرارگيري مناسب ساختمان­ها است كه مي­تواند در كاهش آسيب­هاي ناشي از اين بادها كمك­ كند. اين مقاله به تدوين بهينه گونه حياط­ مركزي ساختمان­ها در برابر بادهاي 120 روزه مي ­پردازد. هدف اين تحقيق تعيين نوع مانع، جهت­ گيري و ميزان محصوريت حياط مركزي است به گونه اي كه بتواند در دو زمينه كاهش سرعت باد و كاهش ورود آلودگي ناشي از گرد و غبار در محدوده­ي ساختمان مفيد واقع شود. در ابتدا مدل هاي مختلف حياط مركزي طراحي و سه بعدي گرديد. شبيه ­سازي جريان­ هوا در اين مدل ها با استفاده از نرم ­افزار شبيه­ سازي سيالات ­Flow 3D انجام پذيرفته است. نتايج نشان مي دهد؛ ساختمان­هايي يا موانعي كه در برابر جهت باد داراي فرم مقعر هستند؛ بيشتر از ساير گونه ها مانع ورود باد به محوطه­ ي سايه باد هستند. همچنين نوع جانمايي و جهت ­گيري ساختمان­ها در برابر باد و ميزان محصوريت در دو نقطه ورود و خروج باد، به همراه استفاده از موانع طبيعي مي­تواند در كاهش سرعت باد و كاهش ورود گرد و غبار به مجموعه تا رسيدن به حد آسايش بسيار موثر باشد.

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