Two-dimensional numerical simulation of wind driven ventilation across a building enclosure with two free apertures on the rear side: Vortex shedding and "pumping flow mechanism". Issue 179 (August 2018)

• Record Type: Journal Article
• Authors: Zhong, Huai-Yu; Zhang, Dong-Dong; Liu, Di; Zhao, Fu-Yun; Li, Yuguo; Wang, Han-Qing
• Is Part Of: Journal of wind engineering and industrial aerodynamics. Issue 179(2018)
• Page Start: 449
• Page End: 462
• Publication Date: 2018-08
• Subjects: Wind-driven natural ventilation -- Single-sided fluid flow -- Vortex shedding -- Numerical simulations; Wind-pressure -- Periodicals; Buildings -- Aerodynamics -- Periodicals; Pression du vent -- Périodiques; Constructions -- Aérodynamique -- Périodiques; Buildings -- Aerodynamics; Wind-pressure; Periodicals
• DOI: 10.1016/j.jweia.2018.07.002
• Languages: English
• ISSNs: 0167-6105

Abstract

Abstract: This paper investigates the single-sided wind driven natural ventilation with two apertures on the rear wall, regarding different horizontal aperture separations, magnitudes of incoming wind speed and various side ratios ( L/D, length/width). In the present work, CFD simulations are performed with Reynolds-Averaged Navier-Stokes (RANS) approach, and pressure correction linked equation is adopted to provide closure. The simulation results indicate that wind flow behind the rear wall is essentially driven by the pumping mechanism due to vortex shedding, in which wind flow direction alternates at a mean rate. The frequency of the "pumping" flow increases dramatically with the wind flow velocity at a wide range of Reynolds numbers. The decrease of free aperture separation reduces the enclosure flow rate whilst the frequency of the wind flow almost maintains at a constant value. The increase of sidewall length has similar impacts on the ventilation frequency and the dimensionless ventilation flow rate. Numerical investigations further demonstrate that non-dimensional ventilation rate can be promoted by increasing incoming wind velocities when the wind speed is less than 5 m/s. This promotion will be restrained when the wind speed is further increased. The simulation results of built enclosure flow rate, frequency of enclosure flow can be applied to improve the ventilation performance of buildings merely with rear wall openings. Highlights: Two-dimensional wind-driven natural ventilation is modeled with two rear wall openings. Wind flow behind the rear wall is driven by the pumping flow mechanism. Vortex shedding frequency depends on geometry and incoming flow magnitude. Ventilation flow rate is independent on the incoming wind flow velocity.