CFD simulation of “pumping” flow mechanism of an urban building affected by an upstream building in high Reynolds flows

• Published in: Energy and buildings Vol. 202; p. 109330
• Main Authors: Zhong, Huai-Yu, Jing, Yi, Liu, Yang, Zhao, Fu-Yun, Liu, Di, Li, Yuguo
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.11.2019; Elsevier BV
• Subjects: Aerodynamics; Air conditioners; Air conditioning; Building blocks; Building design; Computational fluid dynamics; Computer applications; Computer simulation; Energy consumption; Fluid dynamics; Fluid flow; Green buildings; Hydrodynamics; Numerical simulations; Oscillating flow; Oscillation; Pumping; Simulation; Sustainable design; Upstream; Variation; Ventilation; Vortex shedding; Wind; “pumping” wind flow; Numerical simulations; “pumping” wind flow; Building blocks; Oscillation
• ISSN: 0378-7788; 1872-6178
• DOI: 10.1016/j.enbuild.2019.07.047

•Vortex shedding occurred around two identical buildings in tandem arrangement.•Upstream building influences the “pumping flows” of the downstream target building.•Vortex shedding frequencies at various obstacle spacings have been investigated.•“Pumping flow rate” is determined by both mean and fluctuating pressure differences. “Pumping” flow, which is essentially induced by the periodic vortex shedding, was observed when natural wind blows across a single building with two leeward openings. This oscillating flow has been proposed for use to improve wind ventilation of buildings with single-sided openings. Existing studies are limited to a single building block. In this study, effect of an upstream building on the “pumping” ventilation is investigated for various obstacle spacings, by Computational Fluid Dynamics (CFD) simulations. Simulation results show that vortex shedding frequencies could be affected by the non-dimensional obstacle spacing W/B (gap distance/building width), whereas non-dimensional ventilation rate of the downstream building shows a non-linear correlation with the obstacle spacing W/B. Particularly, when W/B continuously increases to 2.0, the ventilation rate reaches the level comparable to that of the isolated block case. Further results also demonstrate that the “pumping” ventilation rates are determined by a combination of mean and fluctuating pressure differences between the leeward openings. The spacing W/B = 2 is the optimal spacing for largest ventilation rate and therefore lowest building energy consumption by Heating, Ventilation and Air Conditioning (HVAC) systems. Our findings could benefit sustainable building design in dense cities.