Simulating the impact of blue-green infrastructure on the local microclimate of urban areas

Started: October 2013
Supervisor: van Reeuwijk, M.Maksimovic, C.

Description of Research

Global population is growing and an increasing part is living in cities. Increasing probability of extreme weather events due to a changing climate and the fact that cities are several degrees warmer than the surrounding rural environment, the urban heat island effect, amplifies the risk of heat waves. Under these conditions urban planners are urged to mitigate the impact of such events. Increasing the greening of facades and roofs offers a feasible possibility to improve thermal comfort and lower heat stress. While theory predicts lower temperatures due to enhanced evapotranspiration from vegetation, little is known about how the air circulation is changed. The plants influence the flow in their vicinity by representing additional roughness, essentially reducing wind velocity close to the surface. The exchange of water and heat modify the airs buoyancy. These effects are important for the ventilation of urban canyons between buildings, where the air often poorly mixes with air aloft but most human activities take place.

The aim of this PhD is to provide a tool that can be used in urban planning to describe the impact of blue-green infrastructure (i.e. vegetation and open water surfaces) on the urban microclimate. This simple model will be based on information and experience we gain from computaional fluid dynamics (CFD). We will develop the capabilities to simulate green infrastructure in an urban environment with an existing atmospheric Large Eddy Simulation (LES) tool. The original model will be extended to allow for realistic flow in highly complex geometries, include momentum, heat and moisture fluxes at the surfaces and treat short- and longwave radiation.

This PhD is part of the Blue Green Dream Project (http://bgd.org.uk/). 

Fig 1
Wind velocity in x-direction (u) over an array of cubes from an LES

Background

Ivo is a graduate with an MSc in Atmospheric and Climate Science from ETH Zurich.

Ivo Suter

Ivo SuterPhD Candidate - Fluid Mechanics 
Department of Civil & Environmental Engineering 
Imperial College London, SW7 2AZ 
i.suter13@imperial.ac.uk