Numerical studies of displacement natural ventilation in multi-storey buildings connected to an atrium

Abstract

This paper describes computational fluid dynamics (CFD) simulations used to investigate displacement natural ventilation in simple multi-storey spaces connected to an atrium. The purpose of the work is to demonstrate the potential of CFD for modelling these airflows using solutions from simple mathematical models and salt bath experiments to provide an indication of the accuracy that can be attained. The storeys are connected to an atrium and air flows into them via top-down-chimneys. The driving force is provided by localised point heat sources on each floor which generate buoyant plumes that entrain the surrounding air and transport warm air upwards forming a warm, stratified layer in each storey. The mathematical models are used to describe the main flow features, such as stratification height, temperature gradient and ventilation flow rate. Results showed that, using the RNG k — ε turbulence model, the predicted airflow patterns, temperature profiles and ventilation flow rates agreed favourably with the mathematical models, demonstrating the potential of using CFD for modelling buoyancy-driven displacement ventilation in multi-storey spaces connected to an atrium.

Practical applications: Computer simulation programs have become valuable tools in the building design process, particularly of innovative buildings. This paper looks at the ability of CFD techniques to model buoyancy-driven natural ventilation in simple multi-storey spaces. The methods used in this paper provide a basis for others to use CFD for predicting natural ventilation in more complex, realistic building structures and are useful for both building designers and CFD practitioners.

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References

Field J. (2000). Breeze blocks. Building Services Journal December 2000; 18—22.

Brecsu. The Queens Building, De Montfort University, Department of the Environment, New Practice Final Report 102. BRE, Garston, 1997.

Brecsu. A performance specification for the energy efficient office of the future. General Information Report 30 BRECSU. BRE, Garston, 1995.

Linden PF , Lane-Serff G. , Smeed DA Emptying filling boxes: The fluid mechanics of natural ventilation. J. Fluid Mech. 1990; 212: 309—35.

Holford JM , Hunt GR Fundamental atrium design for natural ventilation. Building and Environment 2003; 38: 409—26.

Hunt GR and Holford JM Top-down natural ventilation of multi-story buildings. 19th annual AIVC conference, Oslo, Norway, 1998; 197—205.

Cook MJ , Lomas KJ Buoyancy-driven displacement ventilation flows: Evaluation of two eddy viscosity models for prediction. Building Services Engineering Research and Technology 1998; 19: 15—21.

Ji Y. , Cook MJ , Hanby V. CFD modelling of natural displacement ventilation in an enclosure connected to an atrium. Building and Environment 2007 ; 42: 1158—72.

Cook MJ , Ji Y. , Hunt GR CFD modelling of natural ventilation: combined wind and buoyancy forces. International Journal of Ventilation 2003; 1: 169—80.

10.

Ji Y. Numerical studies on natural ventilation flow in an enclosure with both buoyancy and wind effect. The CIBSE national conference London, UK, 2004.

11.

Cibse , Application Manual 10: Natural Ventilation in Non-Domestic Buildings, 1997.

12.

Morton BR , Taylor GI , Turner JS Turbulent gravitational convection from maintained and instantaneous sources . Proc. Roy. Soc. A 1956; 234:: 1—23.

13.

Baturin VV Fundamentals of industrial ventilation, 1972; 3rd edition, Pergamon, Oxford.

14.

Chen Q. Comparison of different kmodels for indoor air flow computations. Numerical Heat Transfer, Part B 1995; 28: 353—69.

15.

Yakhot V. , Orszag SA , Thangham S. , Gatski TB , Speziale CG Development of turbulence models for shear flows by a double expansion technique . Phys. Fluids A 1992; 4: 1510—20.

16.

Versteeg HK , Malalasekera W. An introduction to computational fluid dynamics — the finite volume method. ISBN 0-582-21884-5, 1995.

17.

CFX User Guide Version 4.4, CFX International, Harwell, UK, 2001.

18.

Rhie CM , Chow WL Numerical study of the turbulent flow past an airfoil with trailing edge separation. American Inst. Aeronautics and Astronautics J. 1983; 21: 1527—32.

19.

Nakayama Y. , Boucher RF An introduction of fluid mechanics. ISBN 0340 676493, 1999.

20.

CIBSE Guide C: Reference data. Linacre House, Jordan Hill, Oxford. ISBN 07506 53604, first published 2001.

21.

Hunt GR , Kaye NG Virtual origin correction for lazy turbulent plumes. J. Fluid Mech. 2001; 435: 377—96.