Topic of Research Seminar: On the Predicted Effectiveness of Climate Change Adaptation Measures for Outdoor Thermal Comfort using CFD
Abstract: The urban heat island (UHI) phenomenon has become a major concern for urban sustainability in the wake of global warming and rapid urbanization. This has resulted in increased heat stress and worsened outdoor thermal comfort in urban microclimates. Vegetation, water bodies, and cool materials are one of the most effective strategies to alleviate the adverse effects of rising outdoor temperatures. In this work, CFD simulations have been performed to analyze the effect of more realistic vegetation modeling parameters. The vegetation modeling parameters include the actual form drag coefficient and the variable tree transpiration rate. In addition to that, thermal comfort effectiveness of different tree species with its various morphological characteristics, cool materials’ albedo, and water bodies have also been studied in individual and in combination for a real urban area. The wind flow and heat transfer phenomena are simulated using the unsteady Reynolds-averaged Navier–Stokes (URANS) approach. The simulations were performed with proposed adaptation measures for a real urban area having hot-humid climatic conditions under heat wave conditions. It has been found that for the studied climatic conditions, the consideration of more realistic values of these parameters can yield significant variation in the determination of cooling potential and flow characteristics of applied vegetation. Of all the morphological characteristics, LAD, crown height, and trunk height are found to be most influential in providing thermal comfort. Water bodies promotes improved thermal conditions and urban ventilation in spatial direction. Water and vegetation interventions promote the cooling effect by resulting in low ambient air and surface temperature i.e. 0.9 °C and 3.5 °C;
0.3 °C and 3 °C respectively when compared with reference case. Furthermore, the impact becomes more significant for collective application of these adaptation measures. Cool materials when combined with vegetation and water results in large reduction i.e. 2.2 °C and 1.9 °C in air temperature; and 5.9 °C and 9 °C in surface temperature was observed respectively compared to the reference case. For air flow velocity, it is highest for combined cool materials with water with peak effect at the time of highest solar irradiance.
Subject field of Topic: Urban Physics
Name of Speaker: Muhammad Zeeshan
Professional Rank of Speaker: NUST Student
University Email of Speaker: [email protected]
Affiliation of Speaker: NUST
Date and Venue: October 4, 2022, 1430 – 1600 hrs, NUST School of Mechanical and Manufacturing Engineering (NUST-SMME) Seminar Hall, NUST Islamabad Campus.