Heat and flow dynamics in cities: an experimental comparative study across diverse urban morphologies

Area of Science:

• Urban Climatology
• Environmental Fluid Dynamics
• Atmospheric Science

Background:

• Urban areas exhibit complex atmospheric dynamics influenced by building configurations.
• Understanding urban morphology's effect on flow, ventilation, and heat dissipation is vital for climate management.
• The interaction between thermal buoyancy flow and urban form is not well understood.

Purpose of the Study:

• To investigate heat transport and fluid flow around 3D urban models under buoyancy effects.
• To analyze the influence of urban morphology on non-isothermal urban flow development.
• To quantify differences in ventilation and heat removal performance across varied urban designs.

Main Methods:

• Simultaneous Particle Image Velocimetry (PIV) and Laser-Induced Fluorescence (LIF) measurements were employed.
• Three-dimensional parametric urban models simulating Singapore's morphology were used.
• Buoyancy effects were accounted for in the experimental setup.

Main Results:

• Detailed documentation of non-isothermal urban flow, including heat plume generation and buoyant updraft development.
• Urban morphology variations significantly alter heat and flow mechanisms, impacting ventilation and heat removal.
• Ventilation rates and their fluctuations showed substantial differences, with increases up to 10.5 and 12.2 times, respectively.

Conclusions:

• Urban morphology plays a critical role in modulating thermal-driven buoyancy flows and heat transport.
• Significant variations in ventilation efficiency and heat removal performance are linked to urban design.
• Findings enhance understanding of urban heat dynamics and microclimatic influences of localized thermal effects.