Natural ventilation of an isolated generic building with a windward window and different windexchangers: CFD validation, sensitivity study and performance analysis
Windexchangers are relatively small structures located on the building rooftop to promote natural ventilation. This paper presents a Computational Fluid Dynamics (CFD) validation study, sensitivity analysis and performance comparison of three windexchanger (WE) configurations applied to a generic isolated building with a windward window. The study is limited to wind-driven (isothermal) ventilation, for wind perpendicular to the windward facade. The CFD simulations are based on the 3D-steady Reynolds-Averaged Navier–Stokes (RANS) equations. The validation study is performed with experimental results from a previously published water channel test. The sensitivity analysis focuses on the domain size, grid resolution and turbulence model. The performance evaluation of the three WE configurations is based on the mean velocity and mean static pressure coefficients in the vertical centerplane, the ventilation volume flow rate and the volume percentage of the living zone with air speed ratio equal to or above 0.10. The WE configuration with four openings and one duct shows the highest ventilation flow rate (0.232 m3/s) and the highest volume percentage (21%). This study shows that the assessment and selection of WE configurations should not only be based on volume flow rate or ACH but should consider the living zone air speed ratio as well, specifically concerning the flow distribution in the living zone.
Keywordswindexchanger windcatcher natural ventilation CFD validation
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The authors thank the Eindhoven University of Technology for the software, hardware and office facilities during an academic stay of J.A. Castillo. This work has been partially supported by the PAPIIT-UNAM IN103816 project. J.A. Castillo acknowledges the postdoctoral fellowship grant by the DGAPA-UNAM, the computational facilities provided by the SENER-CONACYT project 260155. J.A. Castillo also is grateful with Dr. Adriana Lira and Dr. Gerardo Oliva for their academic support during the postdoctoral stay. Twan van Hooff is currently a postdoctoral fellow of the Research Foundation Flanders (FWO) and acknowledges its financial support (project FWO 12R9718N). The authors acknowledge the partnership with ANSYS CFD.
- ANSYS (2013). Fluent 15 user’s guide. Lebanon: Fluent Inc.Google Scholar
- Barlow JB, Rae WH, Pope A (1999). Low-Speed Wind Tunnel Testing, 3rd edn. New York: John Wiley & Sons.Google Scholar
- Blocken B, Carmeliet J, Stathopoulos T (2007a). CFD evaluation of wind speed conditions in passages between parallel buildings: Effect of wall-function roughness modifications for the atmospheric boundary layer flow. Journal of Wind Engineering and Industrial Aerodynamics, 95: 941–962.CrossRefGoogle Scholar
- CONAVI (2010). Comisión Nacional de Vivienda, Código de Edificación de vivienda.Google Scholar
- Franke J, Hellsten A, Schlünzen H, Carissimo B (2007). Best Practice Guideline for the CFD Simulation of Flows in the Urban Environment. COST office.Google Scholar
- Khodakarami J, Aboseba MR (2015). Impact of openings’ number and outdoor flow direction on the indoor vertical flow velocity in wind catchers. International Journal of Renewable Energy Research, 5: 325–333.Google Scholar
- Meroney R, Derickson R (2014). Virtual reality in wind engineering: The windy world within the computer. Indian Journal Wind Engineering—Indian Society for Wind Engineering, 11(2): 11–26.Google Scholar