Numerical Modeling of Turbulent Flows Influencing the Dispersion of Atmospheric Pollutants Around a High-Rise Building in an Urban Environment

Abstract: Air pollution in Hanoi represents a pressing public health concern, driven by rapid urbanization and an overwhelming reliance on motorized traffic. This study focuses on evaluating the impact of the Keangnam Hanoi Landmark Tower, standing at 350 meters as Hanoi's tallest structure, on turbulent flows and the dispersion of atmospheric pollutants within a densely populated urban environment. The research employs sophisticated numerical simulations using the Lattice Boltzmann Method (LBM) combined with a block-structured topology-confined mesh refinement approach to model airflow dynamics around the main tower and its two adjacent 212-meter structures. The simulation setup includes a computational domain with defined boundary conditions. Validation with the Kolmogorov scales ensures that the spatial grid size and time step adequately resolves posing the smallest turbulent dissipation scales, confirming the accuracy of the flow and pollutant dispersion patterns. Key findings reveal that recirculation zones and wake vortices trap pollutants in low-velocity areas, elevating local concentrations, and posing respiratory and cardiovascular health risks to residents and pedestrians. Conversely, high-velocity regions around the tower facilitate pollutant dispersion. Moreover, pressure gradients, particularly low-pressure zones in the wake, generate upward suction flows that lift pollutants into higher atmospheric layers, potentially reducing ground-level exposure but increasing concentrations at elevated heights. High-pressure zones on the windward side suppress vertical mixing, further concentrating pollutants near the surface. The study highlights the critical role of urban architectural features in influencing turbulent flow and, by extension, pollution. These insights provide a foundation for developing targeted urban air quality management strategies, such as enhancing natural ventilation, optimizing building layouts, and informing health risk assessments to mitigate the socioeconomic impacts of pollution. The research also identifies gaps in current literature on Hanoi's unique urban context and sets the stage for future investigations.