Study of natural ventilation in buildings by large eddy simulation

Jiang, Yi; Chen, Qingyan

doi:10.1016/s0167-6105(01)00106-4

Cited by 144 publications

(85 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Table 1 summarizes the performance of the three CFD methods in terms of computing time, available airflow information, and accuracy. The results for ventilation rate are the conclusions obtained from Jiang and Chen (2001). In that study, we also reported that FDS subgrid model used in LES is better than the SS model.…”

Section: Figure 2 the Locations Where Comparison Of The Cfd Results supporting

confidence: 80%

“…Table 2 also shows no significant difference between the mean ventilation rate and the average instantaneous ventilation rate. This is different from single-sided, wind-driven ventilation, where the average instantaneous ventilation rate is much higher than the mean value, since the fluctuating flow field plays a more important role there (Jiang and Chen 2001). On the other hand, the mean pressure difference across the opening in the singlesided, buoyancy-driven natural ventilation case is about ten times larger than the fluctuating pressure .…”

Section: Buoyancy-driven Natural Ventilationmentioning

confidence: 70%

“…Based on the definition of ventilation rate, it can be computed by integrating the velocity at the opening. Jiang and Chen (2001) proposed two integration methods. The first one is to extract the mean velocity along the opening, and integrate the mean velocity to get the mean ventilation rate, Q mean .…”

Section: Buoyancy-driven Natural Ventilationmentioning

confidence: 99%

See 2 more Smart Citations

Validation of CFD Simulations for Natural Ventilation

Jiang

Allocca

Chen

2004

International Journal of Ventilation

Self Cite

View full text Add to dashboard Cite

Natural ventilation, which may provide occupants with good indoor air quality and a high level of thermal comfort, and reduce energy costs, has become an important sustainable strategy in building designs. This investigation used three computational fluid dynamics (CFD) models: steady Reynolds averaged NavierStokes equation (RANS) modeling, unsteady RANS modeling, and large eddy simulation (LES) to study both wind-driven and buoyancy-drive natural ventilation. The validation of the CFD models used the experimental data of wind-driven natural ventilation obtained from a wind tunnel with a scaled building model and the data of buoyancy-driven ventilation obtained from a full-scale chamber. LES results seem more accurate and informative than those obtained with the RANS modeling, but with severe penalty in computing time. This investigation has also analyzed turbulence energy spectra of natural ventilation. The peak turbulence energy for wind-driven natural ventilation is at frequencies higher than that for buoyancy driven natural ventilation. Thus, the fluctuating flow field plays a more important role in determining ventilation rate for wind-driven natural ventilation than for buoyancy-driven natural ventilation.

show abstract

Section: Figure 2 the Locations Where Comparison Of The Cfd Results supporting

confidence: 80%

Section: Buoyancy-driven Natural Ventilationmentioning

confidence: 70%

See 1 more Smart Citation

Validation of CFD Simulations for Natural Ventilation

Jiang

Allocca

Chen

2004

International Journal of Ventilation

Self Cite

View full text Add to dashboard Cite

show abstract

“…LES requires a larger time step than DNS; however, the computational cost with LES in terms of the memory and CPU time is larger than for the RANS models. LES was applied to predict the airflow distribution in an enclosed environment, as in the following studies (Davidson and Nielsen, 1996;Emmerich and McGrattan, 1998;Jiang and Chen, 2001;Musser and McGrattan, 2002). General detail on LES can be seen in Sagaut (2002).…”

Section: Computational Approachesmentioning

confidence: 99%

A Ventilation Strategy Based on Confluent Jets : An Experimental and Numerical Study

Janbakhsh¹

2015

Linköping Studies in Science and Technology. Dissertations

View full text Add to dashboard Cite

This study presents air distribution systems that are based on confluent jets; this system can be of interest for the establishment of indoor environments, to fulfill the goals of indoor climate and energyefficient usage. The main objective of this study is to provide deeper understanding of the flow field development of a supply device that is designed based on wall confluent jets and to investigate the ventilation performance by experimental and numerical methods. In this study, the supply device can be described as an array of round jets on a flat surface attached to a side wall. Multiple round jets that issue from supply device apertures are combined at a certain distance downstream from the device and behave as a combined jet or so-called confluent jets. Multiple round jets that are generated from the supply device move downward and are attached to the wall at the primary region, due to the Coanda effect, and then they become wall confluent jets until the floor wall is reached. A wall jet in a secondary region is formed along the floor after the stagnation region.The characteristics of the flow field and the ventilation performance of conventional wall confluent jets and modified wall confluent jets supply devices are investigated experimentally in an office test room. The study of the modified wall confluent jets is intended to improve the efficiency of the conventional wall confluent jets while maintaining acceptable thermal comfort in an office environment. The results show that the modified wall confluent jets supply device can provide acceptable thermal comfort for the occupant with lower airflow rate compared to the conventional wall confluent jets supply device.Numerical predictions from three turbulence models (renormalization group (RNG − ), realizable (Re − ), and shear stress transport (SST − )) are evaluated by measurement results. The computational box and nozzle plate models are used to model the inlet boundary conditions of the nozzle device. In the isothermal study, the wall confluent jets in the primary region and the wall jet in the secondary region, when predicted by the three turbulence models, are in good agreement with the measurements. The non-isothermal validation studies show that the SST − model is slightly better at predicting the wall confluent jets than the other two models. The SST − model is used to i investigate the effects of the nozzle diameter, number of nozzles, nozzle array configuration, and inlet discharge height on the ventilation performance of the proposed wall confluent jets supply device. The nozzle diameter and number of nozzles play important roles in determining the airflow pattern, temperature field, and draught distribution. Increased temperature stratification and less draught distribution are achieved by increasing the nozzle diameter and number of nozzles. The supply device with smaller nozzle diameters and fewer nozzles yields rather uniform temperature distribution due to the dominant effect of mixing. The flow behavior is nearly independent of t...

show abstract

“…This results in lower ventilation rates and air change effectiveness (47). As the inlet air is at a greater velocity, the error will be increased compared to the lower inlet air velocities.…”

Section: Air Supply Ratesmentioning

confidence: 99%

A study of passive ventilation integrated with heat recovery

O’Connor

Calautit

Hughes

2014

Energy and Buildings

View full text Add to dashboard Cite

To meet the demand for energy demand reduction in heating, ventilation and air-conditioning systems, a novel design incorporating a heat recovery device into a wind tower was proposed. The integrated system uses a rotary thermal wheel for heat recovery at the base of the wind tower. A 1:10 scale prototype of the system was created and tested experimentally in a closed-loop subsonic wind tunnel to validate the Computational Fluid Dynamics (CFD) investigation. Wind towers have been shown to be capable of providing adequate ventilation in line with British Standards and the Chartered Institution of Building Services Engineers (CIBSE) guidelines. Despite the blockage of the rotary thermal wheel, ventilation rates were above recommendations. In a classroom with an occupancy density of 1.8m 2 /person, the wind tower with rotary thermal wheel was experimentally shown to provide 9L/s per person at an inlet air velocity of 3m/s, 1L/s per person higher than recommended ventilation rates. This is possible with a pressure drop across the heat exchanger of 4.33Pa. In addition to sufficient ventilation, the heat in the exhaust airstreams was captured and transferred to the incoming airstream, raising the temperature 2°C, this passive recovery has the potential to reduce demand on space heating systems.

show abstract

Study of natural ventilation in buildings by large eddy simulation

Cited by 144 publications

References 17 publications

Validation of CFD Simulations for Natural Ventilation

Validation of CFD Simulations for Natural Ventilation

A Ventilation Strategy Based on Confluent Jets : An Experimental and Numerical Study

A study of passive ventilation integrated with heat recovery

Contact Info

Product

Resources

About