A Wind Tunnel Full-Scale Building Model Comparison between Experimental and CFD Results Based on the Standard k-ε Turbulence Representation

CFD modelling techniques have been used to simulate the coupled external and internal flow in a cubic building with two dominant openings. CFD predictions of the time-averaged cross ventilation flow rates have been validated against full-scale experimental data under various weather conditions in England. RANS model predictions proved reliable when wind directions were near normal to the vent openings. However, when the fluctuating ventilation rate exceeded the mean flow, RANS models were incapable of predicting the total ventilation rate. Improved results are expected by applying more sophisticated turbulence models, such as LES or weighted quasi-steady approximations.

Section: Introductionmentioning

confidence: 99%

A Comparison of CFD and Full-scale Measurements for Analysis of Natural Ventilation

Yang

Wright

Etheridge

et al. 2006

“…They can illustrate the quality of air and temperature distribution and verify whether the ventilation design can provide a satisfactory environment for all occupants (Chow, 1995). Generally, it has been shown that CFD calculated airflows can be in good agreement with measurements (Nishizawa, 2003).…”

Section: Cfd Modellingmentioning

confidence: 96%

Accessing the Thermal Mass above Suspended Ceilings via a Perimeter Gap: a CFD Study of Naturally Ventilated Spaces

Morey

Coley

Kershaw

2010

There is a growing desire to reduce peak temperatures within non-domestic buildings by accessing the thermal mass of separating floors. These floors are typically formed of concrete and can store reasonable amounts of heat. Unfortunately, they are usually thermally isolated from the room below by a suspended ceiling. Therefore, some architects try to access the concrete by leaving a perimeter gap in the suspended ceiling in each room to allow airflow across the underside of the separating floor. For visual and acoustic reasons, there is the desire to make this gap as small as possible. Using computational fluid dynamics we examine the relationship between gap size and airflow above the suspended ceiling for naturally ventilated spaces.We show that although the precise details of the airflow depends on the size of the room, levels of incidental gains, ventilation rates and the location of heat sources, in all cases increasing the perimeter width within realistic bounds results in a linear increase in the mean tangential speed of airflow across the underside of the ceiling. This is common for both single sided and cross ventilated rooms and for both single and double raft designs; however, the double raft design performs significantly better.

“…Van Hooff and Blocken (2010) also applied realizable k-ε models and analysed urban wind flow and indoor natural ventilation using the Amsterdam Arena stadium in the Netherlands as a case study and demonstrated that small geometrical modifications can increase the ventilation rate significantly. Nishizawa et al (2004) showed that the calculated indoor airflow inside a simple building model was strongly influenced by external conditions. Elmualim and Awbi (2002) and Li and Mak (2007) evaluated the performance of wind-driven systems for natural ventilation applications in buildings (based on a commercial wind-catcher design) and showed that it depends mainly on the speed and direction of wind.…”

Section: Whole-domain Approachmentioning

confidence: 98%

Application of CFD in Modelling Wind-Induced Natural Ventilation of Buildings - A Review

Jiru

Bitsuamlak

2010

This paper reviews the application of CFD for designing and parametric studies of wind-induced natural ventilation. The approaches employed in such applications of CFD are whole-domain and domain-decoupled CFD modelling. The domain-decoupled technique separately analyses the external airflow fields outside and internal flows inside a building. In the whole-domain approach, the outdoor and indoor airflow is modelled simultaneously and within the same computational domain. The review showed that the whole-domain approach has been more popular than the domain-decoupled approach, and with efficient computing algorithms, grid generation techniques and advances in hardware technology, can overcome the computational overhead it incurs during application. CFD has also allowed the concept of stream tube and the local dynamic similarity model (LDSM) to be used in practice. These concepts have helped in the fundamental understanding of wind-driven natural ventilation and in distinguishing flow through large openings from that of "cracks". An important and practical approach for natural ventilation design and analysis is the integration of CFD with other simulation programs such as Building Simulation (BS) and Geographic Information Systems (GIS). Apparently, CFD is increasing its importance in sustainable building design and it is expected that more complex naturally ventilated buildings will be designed and analysed as CFD techniques continue to improve.