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

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