Urban fluid mechanics

Building-resolved simulation of outdoor and indoor flow, dispersion, ventilation, and microclimate in cities.

15 people 5 projects 32 papers
UrbanUrban formMicroclimateVegetationDragParameterizationAir QualityDispersionIndoorVentilationShadingSEBLESIBMNWPSensingMachine LearninguDALESWater Management

Cities are the most complicated fluid environments humans build, and the lab’s flagship area is squarely aimed at making sense of them. Using the open-source LES framework uDALES that we develop, we resolve the airflow around individual buildings and trees and chase the consequences from a single street up to a whole neighbourhood — heat, pollutants, ventilation, exposure, all at once.

Tying it together is a coupled urban surface energy balance: multi-reflection radiation between facets, conduction through walls and roofs, sensible and latent heat exchange, vegetation drag and transpiration, and blue-green infrastructure. Recent uDALES work covers parameter studies of the urban SEB (Wilson et al., Q. J. R. Met. Soc. 2025), how shading reshapes the microclimate of an entire city (Wilson et al., Build. Env. 2025), and the coastal-urban diurnal cycle (Owens et al., Build. Env. 2025).

Air quality is the other half of the story. We pair high-resolution dispersion in tree-lined canyons and full neighbourhoods with low-cost sensor networks (Bogaert et al., Sci. Tot. Env. 2024; Schoucair & van Reeuwijk on Gaussian-process nowcasting of NO₂, 2025) and with machine-learning emulators that compress urban land-surface physics into something operational models can actually afford to run (Meyer et al., J. Adv. Mod. Earth Syst. 2022). Indoor-outdoor exchange — classroom exposure, infection risk, the airflow pathways that connect buildings to streets — is treated as part of the same problem, not a separate one.

Sub-kilometre weather prediction needs the same physics in a different form: morphology-aware drag closures that an NWP model can use without resolving every wall. The lab led the WRF-TEB coupling (Meyer et al., GMD 2020; JAMES 2020) and the distributed urban drag framework (Sützl et al., Q. J. R. Met. Soc. 2021).

Active grants in this space include the EU UrbanAIR project (digital twins for urban air quality and heat resilience), the EPSRC exascale turbulence programme (urban work package), and NERC ASSURE (across-scale processes in urban environments).

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