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The Urban Heat Island effect, exacerbated by climate change, poses a significant threat to our environment, significantly impacting people’s lives globally. Primarily, it elevates street temperatures, reducing outdoor activities and social interactions, while amplifying health issues due to excessive heat exposure. To counteract these effects, scientists have developed innovative strategies for acclimatization methods in public spaces, like climate shelters. For this purpose, understanding the airflow dynamics within street canyons is crucial, requiring a comprehensive analysis to gain insight into ventilation mechanisms inside them. Given the labour-intensive nature of real experiments, computational fluid dynamics (CFD) simulations have emerged as a valuable tool, offering rapid and accurate enough outcomes. This research aims to mitigate the lack of information regarding numerical values for air mass flow rates and air renewal within street canyons for a wide range of cases, as well as a study about the number and position of air recirculations formed. Both are essential for designing effective acclimatization strategies. It also presents a novel simplified approach for obtaining the proportion of air coming from outside the street canyon with free-flow temperature. For this purpose, an enhanced numerical domain model, achieved through an optimization process, is provided ensuring high-quality CFD solutions with minimal computational demands and simulation time. This enables two in-depth studies to characterize this phenomenon. Firstly, varying the height-to-width aspect ratio (AR) from wide (AR =0.75) to narrow (AR =4) streets reveals a notable decrease in air renewal as AR increases. This reduction is more pronounced in low to medium AR scenarios, coming to a standstill at higher AR values (AR >2).In addition, in narrow streets there are several recirculations which difficult the air ventilation of the lowest part of the street canyon (ground level floor). Secondly, altering wind speed shows a direct influence on airflow patterns within narrow streets, but not on wide ones, altering the number of recirculations that were expected to be found. Overall, this chapter provides extensive information about air renovation in street canyons, with the ulterior purpose of providing valuable data for subsequent engineering projects aimed at enhancing outdoor acclimatization strategies.

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Ventilation Results and CFD Model Formulation for Street Canyons Applied to Climate Control Strategies

  • 章节

  • 发表日期：

    2025年

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  • Francisco Ruda Sarria,
  • Rafael Monge Palma,
  • Teresa Palomo Amores,
  • Paulo García-Melgar,
  • MPaz Montero-Gutiérrez,
  • MCarmen Guerrero Delgado

摘要

The Urban Heat Island effect, exacerbated by climate change, poses a significant threat to our environment, significantly impacting people’s lives globally. Primarily, it elevates street temperatures, reducing outdoor activities and social interactions, while amplifying health issues due to excessive heat exposure. To counteract these effects, scientists have developed innovative strategies for acclimatization methods in public spaces, like climate shelters. For this purpose, understanding the airflow dynamics within street canyons is crucial, requiring a comprehensive analysis to gain insight into ventilation mechanisms inside them. Given the labour-intensive nature of real experiments, computational fluid dynamics (CFD) simulations have emerged as a valuable tool, offering rapid and accurate enough outcomes. This research aims to mitigate the lack of information regarding numerical values for air mass flow rates and air renewal within street canyons for a wide range of cases, as well as a study about the number and position of air recirculations formed. Both are essential for designing effective acclimatization strategies. It also presents a novel simplified approach for obtaining the proportion of air coming from outside the street canyon with free-flow temperature. For this purpose, an enhanced numerical domain model, achieved through an optimization process, is provided ensuring high-quality CFD solutions with minimal computational demands and simulation time. This enables two in-depth studies to characterize this phenomenon. Firstly, varying the height-to-width aspect ratio (AR) from wide (AR =0.75) to narrow (AR =4) streets reveals a notable decrease in air renewal as AR increases. This reduction is more pronounced in low to medium AR scenarios, coming to a standstill at higher AR values (AR >2).In addition, in narrow streets there are several recirculations which difficult the air ventilation of the lowest part of the street canyon (ground level floor). Secondly, altering wind speed shows a direct influence on airflow patterns within narrow streets, but not on wide ones, altering the number of recirculations that were expected to be found. Overall, this chapter provides extensive information about air renovation in street canyons, with the ulterior purpose of providing valuable data for subsequent engineering projects aimed at enhancing outdoor acclimatization strategies.