Group Leader & Senior Scientist · ETH Zürich

Yongling Zhao
Cooling cities through fluid physics.

I study urban climate, multiscale heat transfer, and fluid mechanics — from the transition physics of thermal boundary layers to how trees, wind, and buoyancy shape heat in real cities. My goal: science that helps cities beat the heat.

Explore research Google Scholar ↗
40+
Peer-reviewed publications
2013 2026
J. Fluid Mech. to Nature Communications
IHTC-16
Keynote, Int. Heat Transfer Conf.
5 cities
Cross-city cooling trend analysis
01 / about

About

I am a Group Leader at the Chair of Building Physics (CBP) and Senior Scientist (Oberassistent) and Lecturer in the Department of Mechanical and Process Engineering at ETH Zürich. My research sits at the intersection of fluid engineering and multiscale heat transfer for sustainable systems and climate.

I earned my PhD in fluid mechanics from the University of Sydney, where my work on the transition of natural convection boundary layers revealed resonance-triggered heat transfer enhancement and controlled transition mechanisms — published in the Journal of Fluid Mechanics. As a Visiting Scholar at the University of Cambridge (SNSF scientific exchange grant), I broadened this foundation toward urban-scale flows.

Today my group combines water-tunnel PIV–LIF experiments, CFD and WRF simulations, and machine learning to understand and mitigate urban heat — from street-canyon buoyancy and tree cooling to city-scale heat island dynamics and heat-related policy.

I serve as a guest editor at Building and Environment and on the editorial board of City and Built Environment, and I am always open to multidisciplinary collaboration.

02 / research

Research

From fundamental transition physics to machine-learning-assisted urban climate science — six threads, one goal: cooler, more livable cities.

R·01

Urban heat mitigation pathways

Prioritizing nature-based solutions and technological innovations to accelerate cooling — and aligning urban cooling strategies with global warming trends across Hong Kong, Sydney, Montreal, Zurich, and London.

trend analysis · cooling degree hours · policy
R·02

Buoyant flows in street canyons

Quantifying how thermal buoyancy interacts with wind and canyon morphology to govern heat removal, pollutant dispersion, thermal comfort, and building energy use.

water tunnel · CFD · scaling analysis
R·03

Cooling power of urban trees

Coupled airflow–heat–moisture–radiation simulations of vegetation in street canyons, including tree-size effects on nighttime microclimate under real heatwave conditions.

OpenFOAM · 2019 Zurich heatwave data
R·04

Machine learning for urban heat

Validated WRF simulations combined with ML to disentangle how urban morphology, anthropogenic heat, and wind dynamics drive heat islands during heatwaves — and to map city-scale air temperature.

WRF · ML · city-scale mapping
R·05

PIV–LIF flow & heat diagnostics

Concurrent velocity–temperature field measurements with non-toxic dyes in large water tunnels — decisive progress enabling laboratory modelling of urban heat.

PIV · LIF · experimental methods
R·06

Transition of thermal boundary layers

DNS-based stability analysis and laser diagnostics of laminar–turbulent transition in natural convection — resonance-triggered heat transfer enhancement and controlled transitions.

DNS · stability analysis · J. Fluid Mech.
03 / publications

Selected publications

40+ peer-reviewed articles. A selection below — full list on Google Scholar ↗

2026

Asymmetric global urban cooling potential demands accelerated and context-specific actions

Ding X, Fan Y, Zhao Y, Ürge-Vorsatz D, Ge J, Carmeliet J et al. · Nature Communications 17, 4239
2023

The time-evolving impact of tree size on nighttime street canyon microclimate

Zhao Y*, Li H, Bardhan R, Kubilay A, Li Q, Carmeliet J · Urban Climate 49, 101528
2023

Machine learning-assisted mapping of city-scale air temperature

Ding X, Zhao Y, Fan Y, Li Y, Ge J · Building and Environment 234, 110211
2023

Urban heat dome flow deflected by the Coriolis force

Zhang Y, Wang X, Fan Y, Zhao Y*, Carmeliet J, Ge J · Urban Climate 49, 101449
2022

Enhancement of heat removal from street canyons due to buoyant approaching flow

Zhao Y*, Xue Y, Mei S, Chao Y, Carmeliet J · Building and Environment 226, 109757
2022

Impact of green walls on ventilation and heat removal from street canyons

Li H, Zhao Y*, Sützl B, Kubilay A, Carmeliet J · Building and Environment 214, 108945
04 / teaching

Teaching & supervision

course · ETH Zürich · since 2019

Urban Physics — Lead Lecturer

The state of the art in urban climate research: urban heat islands, urban wind, vegetation, thermal comfort, and climate mitigation strategies. Each semester includes hands-on workshops with laboratory tests and field measurements, plus invited speakers — including Prof. Diana Ürge-Vorsatz (2023).

supervision & resources

Master's theses & open materials

I supervise Master's projects on topics such as:

  • Machine learning for urban climate and heat mitigation
  • Aerodynamic and thermal effects of urban vegetation

I also share PIV learning resources — code, particle images, lecture notes, and video demonstrations.

05 / contact

Let's collaborate

Open to multidisciplinary research and collaboration across fluid mechanics, urban climate, heat mitigation, and data-driven approaches to sustainable cities.

LEO C 2 · Leonhardstrasse 27 · 8092 Zürich · Switzerland
Dept. of Mechanical and Process Engineering, ETH Zürich