Modified 'closure' constants of the Standard k-ε turbulence model for the prediction of wind-induced natural ventilation

Stavrakakis, GM; Tomazinakis, NM; Markatos, NC

dc.contributor.author	Stavrakakis, GM	en
dc.contributor.author	Tomazinakis, NM	en
dc.contributor.author	Markatos, NC	en
dc.date.accessioned	2014-03-01T02:11:27Z
dc.date.available	2014-03-01T02:11:27Z
dc.date.issued	2012	en
dc.identifier.issn	01436244	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/29905
dc.subject.other	Computer resources	en
dc.subject.other	Energy reduction	en
dc.subject.other	Experimental data	en
dc.subject.other	In-buildings	en
dc.subject.other	Modified model	en
dc.subject.other	Natural ventilation	en
dc.subject.other	Numerical results	en
dc.subject.other	Pressure coefficients	en
dc.subject.other	Streamwise velocity	en
dc.subject.other	Vertical velocity components	en
dc.subject.other	Wind characteristics	en
dc.subject.other	Computational fluid dynamics	en
dc.subject.other	Prandtl number	en
dc.subject.other	Troposphere	en
dc.subject.other	Turbulence models	en
dc.subject.other	Ventilation	en
dc.title	Modified 'closure' constants of the Standard k-ε turbulence model for the prediction of wind-induced natural ventilation	en
heal.type	journalArticle	en
heal.identifier.primary	10.1177/0143624411407950	en
heal.identifier.secondary	http://dx.doi.org/10.1177/0143624411407950	en
heal.publicationDate	2012	en
heal.abstract	In this study, wind-driven natural ventilation in buildings is investigated by means of computational fluid dynamics. The airflow in and around three pilot buildings, which correspond to the most common natural-ventilation designs, i.e. cross-, windward- and leeward- single-sided ventilation, is simulated by applying both the Standard and a modified k-ε turbulence model. The latter represents a Prandtl number-modified version of the Standard k-ε model, based on the flow-variable (velocity and turbulence variables) distributions and on the atmospheric boundary layer (ABL) assumptions. Numerical results of streamwise and vertical velocity components, as well as of pressure coefficients at the facades, obtained by both turbulence models are compared with available wind tunnel experimental data found in literature. It is concluded that both models applied are in acceptable agreement with measurements, especially for the mean streamwise velocity component, while the proposed modified model is more accurate as far as flow within the windward and the internal parts (i.e. within the building) of the domain is concerned.Practical application: This study focuses on the development of a modified k-ε turbulence model for the prediction of wind-driven natural ventilation. The analysis described represents a methodology to produce 'closure' parameters, such as Prandtl numbers, compatible with the incoming wind characteristics (ABL). It was found that for all ventilation cases studied, i.e. cross- and single-sided ventilation, the proposed modified model is more accurate compared with the Standard k-ε model, and it accounts for the dumping effect near the walls and for kinetic energy reduction in the impinging region adequately. It is satisfying that the modified k-ε model leads to acceptable engineering results within relatively practical computer resources. © The Chartered Institution of Building Services Engineers 2011.	en
heal.journalName	Building Services Engineering Research and Technology	en
dc.identifier.doi	10.1177/0143624411407950	en
dc.identifier.volume	33	en
dc.identifier.issue	3	en
dc.identifier.spage	241	en
dc.identifier.epage	261	en