Investigation of varying louver angles and positions on cross ventilation in a generic isolated building using CFD simulation. Issue 229 (October 2022)

• Record Type: Journal Article
• Authors: Tai, Vin Cent; Kai-Seun, Joseph Wu; Mathew, Prasath Reuben; Moey, Lip Kean; Cheng, Xinwei; Baglee, David
• Is Part Of: Journal of wind engineering and industrial aerodynamics. Issue 229(2022)
• Publication Date: 2022-10
• Subjects: Natural cross ventilation -- Louver angle -- Isolated building -- Air exchange efficiency -- CFD; Wind-pressure -- Periodicals; Buildings -- Aerodynamics -- Periodicals; Pression du vent -- Périodiques; Constructions -- Aérodynamique -- Périodiques; Buildings -- Aerodynamics; Wind-pressure; Periodicals
• DOI: 10.1016/j.jweia.2022.105172
• Languages: English
• ISSNs: 0167-6105

Abstract

Abstract: Louvers are an integral component of natural ventilation. This study presents a numerical analysis using computational fluid dynamics (CFD) on cross ventilation in an isolated building equipped with louvers. Opening configurations of (i) center-center, (ii) top-top, (iii) bottom-bottom, (iv) top-bottom and (v) bottom-top (whereby the configurations are defined as 'windward'-'leeward') with varying louver configurations of No-Louver (NL), 0°, 15°, 30° and 45° are studied. Atmospheric Boundary Layer (ABL) condition is applied at the inlet of the flow domain and Renormalization Group (RNG) k-ε turbulence model with enhanced wall function (EWT) is employed for the numerical simulations. Grid sensitivity analysis is performed using Grid Convergence Index (GCI) whilst model validation is performed using Factor of two of observation (FAC2) analysis. The highest dimensionless flow rate (DFR) is achieved by configuration top-top without louvers at 0.719. The highest air exchange efficiency (AEE) is obtained by louver angle of 15° for center-center configuration at 53.4%. The lowest AEE obtained is obtained at louver angle of 0° for top-top configuration at 20%, indicating short-circuiting of air. For configuration bottom-bottom with louver angle of 30°, high AEE is obtained but at the cost of reduced DFR. The optimal balance between AEE and DFR can be obtained by factor-optimization (α) as presented in this paper. The study concludes that opening position alongside louver angle plays an integral role on the internal airflow, pressure coefficient, DFR and AEE in natural cross ventilation. Highlights: Configurations with symmetrical openings, center-center, top-top and bottom-bottom with 0° louvers cause short-circuiting of air. Contrarily, configurations top-bottom and bottom-top with 0° louvers improve the mixing of air in the building. Highest air exchange efficiency (AEE) is obtained by center-center with louver angle of 15° at 53.4%, meanwhile the lowest AEE is obtained by configuration top-top with louver angle of 0° at 20%. A higher dimensionless flow rate (DFR) is not synonymous with higher AEE. For certain configurations such as bottom-bottom with louver angle of 30°, high AEE is obtained at 50.5% but at the cost of reduced DFR. With that in mind, DFR should be prioritized in this configuration. Balancing the tradeoff between AEE and DFR can be done using factor-optimization, α as shown in this paper.