Coherent structures and wind force generation of square-section building model

F. Wang, K. M. Lam, G. B. Zu, L. Cheng

Research output: Journal article publicationJournal articleAcademic researchpeer-review

19 Citations (Scopus)


Typical flow topology of Karman type and arch type vortex shedding from two square-section building models with aspect ratios 2 and 6 is revealed by space-time analysis of fluctuating velocity fields and surface pressure signals obtained by synchronized time-resolved particle-image velocimetry (PIV) and multi-port pressure scanning. Proper orthogonal decomposition (POD) is applied to the PIV data with a pretreatment step to extract the two types of vortex patterns based on their inherent antisymmetry and symmetry features on the horizontal plane about the wake centerline. The antisymmetric POD modes have the general mode shapes of a row of single vortices of alternating rotation senses along the wake centerline, while the mode shapes of the symmetric POD modes show successive pairs of counter-rotating vortices along the wake centerline. When combined with the time-averaged base flow of the wake featuring two stationary recirculating bubbles, the two types of POD modes exhibit the respective vortex patterns of Karman and arch type. The roles of these coherent structures on the generation of fluctuating across-wind force, especially during occurrence of peak force magnitudes, are explored with reconstruction of peak flow events from the lower-order POD modes. The study provides a new insight into the evident connection between the quasi-cycles of antisymmetric POD modes and the generation of quasi-periodic across-wind force.

Original languageEnglish
Pages (from-to)175-193
Number of pages19
JournalJournal of Wind Engineering and Industrial Aerodynamics
Publication statusPublished - May 2019
Externally publishedYes


  • Building wake
  • PIV
  • POD
  • Vortex shedding
  • Wall-mounted cylinder wake

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Renewable Energy, Sustainability and the Environment
  • Mechanical Engineering


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