Investigating the Architectural Adaptation of the Kharkhaneh Chamber of Machi Castle (Safavid Period) with 120-Day Winds in the Ancient City of Howzdar Sistans

The warm and arid climate of the Sistan area has given the people of Sistan valuable experiences to adapt to the environment through various historical periods. Therefore, it is necessary to recognize and use historical experiences such as the “Kharkhaneh Machi Castle” as one of the Safavid antiquities in adaptation to the environment. Therefore, the purpose of this study was to investigate the conformity of the Kharkhaneh Machi Castle architecture with 120-day wind speed of Sistan. The present research question is how did the chamber of Kharkhaneh Machi Castle perform Computational Fluid Dynamics (CFD) in terms of structural adaptation to the 120-day winds of Sistan at an average velocity of 6.5 m/s? The research method is descriptive-analytical and based on documentary, library and field studies in the ancient city of Howzdar Sistan and Machi castle. CFD software has been used to simulate the wind. Due to the complexity of the architecture, the geometrical volume of the Machi castle was produced in Ansys and 3D Max software. Production of network independence was performed with Ansys Meshing software. Meteorological data and WRPLOT View software were used to identify the wind parameters. The CFD simulation results show that the “wind speed” in the valve and interior part of the Kharkhaneh chamber covers a numerical range between 4/93e+00 to 9/87e-01. Also, when facing the exit door (southwest room door) it has the largest numerical range between 2/96e+00 to 1/97e+00. In addition, the “direction of the wind” hits the south wall as soon as it enters the Kharkhaneh directly and slightly to the right. The wind direction in the north porch is rotated, causing air circulation and air conditioning in the north porch room and Kharkhaneh chamber. CFD results and archaeological data confirm the favorable operation and use of the 120-day Sistan winds during the warm months of the year in the Kharkhaneh chamber of Machi Castle.
Keywords: Howzdar City, Sistan, Machi Castle, Kharkhaneh, Wind, CFD.
 
Introduction
Sistan region in eastern Iran has unique features. The area is known as the “Land of the Wind” due to the long and various winds, “especially 120-day winds”, and the persistence of these winds throughout the year, with significant strength and speed. Therefore, it differs from many other windy regions of Iran. The 120-day winds of Sistan are mostly flowing from north and northwest. On the other hand, the climate of this region, with the maximum annual temperature above 40 ’C and the long summer season, has created difficult natural conditions. This has led to people’s initiatives in understanding the process and mechanism of wind flow and the ways in which it can be used in architecture. In this respect, the “Kharkhaneh” are the architectural structures that are admirably built to suit the environmental and climatic conditions of the area. The ingenuity of this architecture demonstrates their clever use of nature. Understanding how the wind flows, functions, and adaptation of Kharkhaneh to 120-day winds will help archaeologists discover and present a relevant and scientific analysis of living conditions in hot and dry areas. Accordingly, the use of appropriate techniques and techniques for archaeologists is essential for the analysis of wind conditions in difficult climates. One of the most valuable examples in the field of architecture is the “Kharkhaneh Room of Machi Castle”, which is used as a model of ancient architecture to refine modern architecture. Since the average 120-day wind speed, recorded by Zabol Meteorological Station in June, July, August, and September, is about 6.5 m/s, therefore, the purpose of this study was to investigate the compatibility of the Kharkhaneh Room of Machi Castle (Safavid period) with the average speed of these types of winds under normal conditions. In this study, the most powerful Computational Fluid Dynamics (CFD) method is used to analyze the wind flow condition of Machi Castle. So, the most important research question is: How did the Sistan Kharkhaneh Room of Machi Castle perform in terms of building compliance with the 120-day wind direction of Sistan and an average speed of 6.5 m/s?
 
Discussion
The Machi Castle is located in a Howzdar area, 60 km southwest of Zabol city, between the Shahr-e Sukhteh and Tasuki towns. According to meteorological data, with the onset of the prevailing winds (120-day wind of Sistan) in May to September, the average of these winds has been determined. Due to the large volume of simulation operations and the variety of output scenarios, the average wind speed of 6.5 m/s was performed on the Kharkhaneh Room of Machi Castle by Ansys Fluent software.
Wind current simulation with average speed of 6.5 m/s and effects and direction of 120-day winds speed has been analyzed once with the hypothesis of “opening the valve of the Kharkhaneh and the door of the room” and again with the hypothesis of “closing the valve of the Kharkhaneh and the door of the room” in the outer and inner space of the Kharkhaneh. CFD simulation results in the northern part of the Machi Castle, “wind speed”, show numerical ranges with the highest range of 9/86e+00 to the lowest range of 1/16e-03. In addition, the wind speed in the valve and interior part of the Kharkhaneh Room ranges from 3/95e+00 to 5/92e+00. The “direction of the wind” also indicates that as soon as the wind enters the Kharkhaneh Room, it hits the south wall directly and slightly bent to the right. After collisions and lateral disturbances, the wind flows to the northern porch of the castle because of the cabinet door in the southwest, and then enters the central courtyard of the castle via the northern porch.
 
Conclusion
CFD simulation with an average wind speed of 6.5 m/s, in the north side of the Machi castle, shows the wind speed and direction in the valve and interior part of the Kharkhaneh. Since there is an interior wall opposite the direct current wind at the end of the Kharkhaneh room, after the wind has hit the wall, it flows to the west or to the door of the Kharkhaneh room and then enters the north porch. Also, the simulation results of the “wind direction” show that the wind direction has found its way out to the north porch of the castle due to the Kharkhaneh door in the southwest. Based on the different results and outputs, understanding how the function of Kharkhaneh Room of Machi Castle and adapting its architecture to the north and northwest directions, the average 120-day wind speeds of Sistan during the warm months of the year are confirmed in the Safavid period. The present study is the first archaeological research into the impact of wind on the architecture of the castle.