Evaluation of the effect of physical structure on the wind flow pattern in urban environments (case study: Siyah-Poshan and Gozare Shahi neighborhoods in Ghaleh district of Dezful)

Introduction:
Nowadays, cities are facing problems such as overheating caused by urban congestion, causing thermal islands and environmental problems, which make life difficult in some places. The wind flow in the urban environment is an important factor affecting the exchange of heat and moisture, particle transport, and urban ventilation. Studies show that physical factors such as enclosure change, the elevation of buildings, and different orientations of passageways in urban texture affect the speed and direction of the wind flow. The purpose of this study was to analyze climate data related to wind flow in two urban areas of Dezful and investigate the effect of enclosure of passages on the wind flow.
Material and methods:
In order to carry out the study, two areas of Siah-Pushan and Gozare-Shahi in the range of historical texture of Dezful, with similar and different physical factors, were selected for the analysis of physical conditions by comparing climate data. Data on the intensity of the wind and the ambient temperature of both areas in five periods of 9 -11 am, 11am-1 pm, 2-4 pm, 4-6 pm, and 6-8 pm, and in two seasons, winter and summer, were selected. Then, the enclosure of the collected points was calculated and using the linear regression analysis, the relationship between enclosure and wind speed was assessed.
Results and discussion:
The results showed that the velocity of the southwest-northeast wind flow was more than other orientations. Also, surveys showed that increasing the specific enclosure can increase the wind speed by a certain magnitude. In Gozare-Shahi, the results of the regression diagrams in the winter indicated that a direct relationship exists between the enclosure of the cross-sections and the velocity of the wind. With the minimum enclosure (0.35) increasing 1.5 to 3 times, the initial velocity of wind increased up to 31- 121 percent. The results of the linear regression diagrams in Siah-Pushan indicated that with 2 to 6 times increase in the enclosure, the wind speed increases up to 1.1 to 1.8 times. The results obtained from the linear regression diagrams in Gozare-Shahi passage showed that the enclosure of passways and the velocity of the wind flow are directly correlated. With the minimum enclosure (0.35) increasing 1.5 to 3 fold, the initial velocity of the wind increased 10 to 40 percent. In Siah-Pushan range, the enclosure of transitions was directly correlated with the wind. Also, the results showed that by increasing the enclosure up to 2 to 6 times, the velocity of the wind increased 1.03 to 1.20 times.
Conclusion:
Increasing the velocity of the wind led to better ventilation in the urban environment. On the other hand, increasing the enclosure increased the velocity. Uniform buildings, as well as regular enclosures with the least changes, will increase the velocity of the wind stream, as well as less turbulence. Thus, increasing enclosure, as well as regular buildings, can ultimately lead to better urban environments.