This paper presents a trial of applying a CFD package into an air movement study in an old English church. The possibility of adopting computational modelling in a complex shaped building has highlighted the problem encountered due to the large difference in scale between thermal elements and building enclosure. The results have demonstrated that there are still significant problems to be overcome in using CFD models in such situations.
Tracer-gas techniques are widely used for measurement of airflow in buildings and their accuracy depends critically on the uniformity of tracerlair mixing. However, tracer mixing is still an unsolved problem and the effect of many factors remains unclear. This paper presents a study of the effect on mixing of tracer species. The investigation concentrated on tracer mixing involved in the decay technique, which is the most widely used version of the tracer gas method.
The work was concerned with measuring natural convection through a large horizontal opening of different sizes and shapes located between two rooms in a building. Airflow rates between the two rooms were measured using a tracer-gas decay technique. Room 1 was heated to various temperatures in the range 18°C to 33°C using thermostatically controlled heaters; room 2 was unheated. A multi-point sampling unit was used to collect tracer-gas samples from each room. The concentration of SF6 tracer was measured using an infra-red gas analyser.
As proposed in IEA Annex 20, a two dimensional case, for which detailed experimental data are available, has been specified by Nielsen to test different CFD codes. This report presents the results computed by the FLUENT code and he comparison between the computed results of thisreport and Chen and between measured results presented by Nielsen.
Computational fluid dynamics has been used for assessing the thermal comfort and air quality in an office ventilated with a displacement system for a range of supply air conditions. Thermal comfort is predicted by incorporating Fanger's comfort equations in the airflow model. Indoor air quality is assessed according to the predicted contaminant concentration and local mean age of air. The performance of the displacement ventilation system is then evaluated based on the predicted thermal comfort and indoor air quality.
Starting from the basic governing equations for fluid flows, a three-dimensional computational fluid dynamics (CFD) code is described. The pre-processing and post-processing software was integrated with the CFD code to form a more user-friendly computer package. This new computer package has been used to carry out several simulations on air and smoke movement in atrium with balconies. It has been found that the pre?processing and post-processing software can greatly reduce the data preparation and analysis time. It can also reduce the likelihood of making errors in data entry.
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