Impact of building separation on natural ventilation behaviour and performance for low-rise structures

James O P Cheung, Chun Ho Liu, Chi Ho Michael Yam

Research output: Chapter in book / Conference proceedingConference article published in proceeding or bookAcademic researchpeer-review

Abstract

Natural ventilation, a readily available natural resource, should be better utilized for integrating the concept of sustainability in our built environment. Obviously, the clearance among buildings is a crucial factor affecting the natural ventilation performance. This paper attempts to reveal the ventilation behaviour in urban geometry of different building spacing. Large-eddy simulations (LES) were performed with the one-equation subgrid-scale (SGS) model for the unresolved turbulent kinetic energy. Three evenly separated two-dimensional (2D) hypothetical buildings were aligned in the streamwise direction that made up the computational domain. Cross-ventilation was enabled by opening up the lower halves of the windward and leeward facades. The Reynolds number was prescribed at around 50,000 to ensure fully developed turbulent flow. The sensitivity of the ventilation rate and the flow pattern in and around the buildings to building separation was examined. Fresh air entrainment from the shear layer aloft was significantly suppressed when the building separation was small. Reversed flow and recirculations were dominated near the ground and within the building envelope. Changes in the flow pattern, such as the positions, the sizes and the intensities of the recirculations, were observed with increasing separation. The contribution of turbulence to the total ventilation rate differed by various extents. When the separation approached 1.5 times the building height, the mean ventilation flux across the building envelope dropped to almost zero while the turbulent flux dominated the ventilation.
Original languageEnglish
Title of host publicationHARMO 2010 - Proceedings of the 13th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes
PublisherARIA Technologies
Pages755-759
Number of pages5
ISBN (Electronic)9782868150622
Publication statusPublished - 1 Jan 2010
Event13th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes, HARMO 2010 - Paris, France
Duration: 1 Jun 20104 Jun 2010

Conference

Conference13th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes, HARMO 2010
CountryFrance
CityParis
Period1/06/104/06/10

Keywords

  • Building interference
  • Computational fluid dynamics (CFD)
  • Cross ventilation
  • Large-eddy simulation
  • Natural ventilation
  • Urban geometry

ASJC Scopus subject areas

  • Modelling and Simulation
  • Atmospheric Science
  • Pollution

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