The wind load issues play a significant role in designing tall buildings, which has sometimes been considered an even more essential factor than earthquake loads. Also, investigating wind behavior in tall buildings is a crucial issue in architectural and structural design. A primary concern of wind engineering and aerodynamics is drag force. Drag force refers to a solid object’s behavior in the relative wind flow velocity direction in terms of fluid dynamics. The investigation involved only drag forces. The Autodesk Flow Design 2014 software was utilized as a wind tunnel simulator. The Large Eddy Simulation (LES) method was used for turbulence solving. This study aims to optimize tall square and triangular-shaped buildings in order to reduce drag force under along-wind motion. For this purpose, architectural aerodynamic strategies such as chamfered, rounded, and recessed corners were applied as aerodynamic modifications. Moreover, aerodynamic forms, including tapering and setting back on shapes, were applied on 24 building models. Generally, the height (H) and breadth (b) ratios were set to H: 200 m, which is equivalent to almost 60 stories, and b: 25 m wide. The obtained results indicate that model S5 (with a square floor plan) achieved 0.65 CD, and the t1 (with a triangular floor plan) achieved 0.30 CD, which could provide the best building model to reduce drag force. In this regard, the s1 could perform over 50% better in reducing wind load. Concerning the aerodynamic modification performance, the simulation results indicate that these modifications were able to lead to over 50% better performance in reducing wind force in square samples compared to triangular samples.

Today, renewable resources and the crucial role of passive strategies in energy efficiency in the building sector toward the sustainable development goals are more indispensable than ever. Natural ventilation has traditionally been considered as one of the most fundamental techniques to decrease energy usage by building dwellers and designers. The main purpose of the present study is to enhance the natural ventilation rates in an existing six-story residential building situated in the humid climate of Rasht during the summertime. On this basis, two types of ventilation systems, the Double-Skin Facade Twin Face System (DSF-TFS) and Single-Sided Wind Tower (SSWT), were simulated through DesignBuilder version 4.5. Then, two types of additional ventilation systems were proposed in order to accelerate the airflow, including four-sided as well as multi-opening wind towers. The wind foldable directions were at about 45 degrees (northwest to southeast). The simulation results show that SSWT could have a better performance than the aforementioned systems by about 38%. Therefore, the multi-opening system was able to enhance the ventilation rate by approximately 10% during the summertime.

The study of wind behavior around tall buildings is a critical issue in architectural and structural design. Therefore, Tall modern buildings are extremely sensitive to the wind. Thus, the assessment of wind loads to design these buildings is essential. Monitoring the wind, which is forcing extraordinary tall buildings is highly challenging. By looking at recent constructions in Iran, it is obvious that despite the fact that constructing tall buildings is spreading, there is less concentration on environmental factors such as wind's aerodynamic. The purpose of this study is to introduce a theoretical framework. Hence, by using CFD simulation, investigating on wind speed in various regions of the tall-triangular building have been focused. Finally, Autodesk Flow Design 2014 software is utilized to present a CFD simulation of a building model with a triangular footprint, Rounded Corner aerodynamic correction, and Set-back aerodynamic form. These simulations have been looking forward to finding out about how can aerodynamic forms affect pressure zone reduction in buildings and reduce wind flow pattern in urban regions.