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STUDY OF THE MITIGATION STRATEGIES
FOR AIRBORNE TRANSMISSION IN
HIGH-RISE DRAINAGE PIPE
Poster
YEUNG Man Ho
BEng (Hons) in Building Services Engineering
Department of Construction, Environment and Engineering
OBJECTIVES RESEARCH BACKGROUND
• To analyze how vent pipe length Airborne transmission through high-rise drainage systems poses a critical
(1.5m vs. 2.5m) affects aerosol public health risk, as demonstrated by COVID-19 outbreaks in Hong Kong
backflow using CFD simulations. (e.g., Heng Tai House in Tai Po). Contaminated aerosols escape roof vents and
• To evaluate seasonal wind impacts re-enter upper floors via turbulence-driven backflow, bypassing water seals.
(summer: 5.08 m/s; winter: 10.33 Conventional solutions like standard 80mm vent pipes fail to address this, as
m/s) on aerosol dispersion patterns. they terminate within turbulent boundary layers. This project investigates how
• To propose design modifications optimizing vent pipe design—particularly length and diameter—can mitigate
(e.g., extended pipes, larger aerosol dispersion. The study is vital for urban health, offering evidence-based
diameters) for reducing airborne upgrades to building codes and retrofits in densely populated cities.
transmission risks in high-rises.
METHODOLOGY
The study employs Computational Fluid Dynamics (CFD) in Ansys Fluent to
simulate airflow in a 3D model of floors 28–32 of Heng Tai House. A hexahedral
mesh (490k elements) captures boundary layers, with 80mm pipes as the
baseline. Seasonal wind data (Hong Kong Observatory, 2020) drives velocity
inlet conditions. Two cases are compared: 1.5m (current standard) and 2.5m
vent pipes. Multiphase simulations (air + water droplets) analyze aerosol
dispersion. Results are validated via velocity streamlines and particle traces,
focusing on aerosol re-entry near upper-floor windows. The methodology
ABOUT THE INVESTIGATOR bridges architectural design with fluid dynamics to quantify transmission risks.
A final-year Building Services Engineering FINDINGS
student passionate about sustainable
urban design and public health. CFD results demonstrate that 2.5m vent pipes reduce aerosol backflow by
With expertise in CFD modeling and elevating emissions above the turbulent boundary layer. In summer (5.08 m/s),
Piping & Drainage systems, I aim to thermal updrafts disperse aerosols vertically, while winter winds (10.33 m/s)
bridge engineering solutions with enhance horizontal dispersal. The longer pipe configuration shows near-zero
epidemiological challenges. This window contamination, unlike the 1.5m pipe, which recirculates aerosols into
project reflects my commitment to living spaces. Pipe diameter increases further stabilize airflow by reducing
creating safer built environments pressure transients, protecting water seals. These findings align with Wong et
through evidence-based innovation. al. (2013) on pressure dynamics. The study confirms that simple design changes
My career goal is to contribute to are cost-effective and scalable. This can significantly mitigate transmission
smart city development with a focus risks, supporting updates to building codes and retrofit protocols in high-density
on airborne infection control. My FYP urban areas.
supervisor is Dr Phil ZHOU.
07 Student Applied Research Presentations 2025 Student Applied Research Presentations 2025
