Methodology for the Evaluation of Natural Ventilation in ... - Cham

phenomena of airflow patterns and in some cases temperature and pressure distributions.Depending on the case of natural ventilation being modeled, there are influencing factors such asthe fluid used, scale and model type that affect the decision as to the method to use. Each ofthese factors can influence the resulting data, as will be discussed in the next chapter,Dimensional Analysis and Similitude. The modeling methodology developed for this researchinvestigates each of the natural ventilation cases, using air as the fluid and comparing theexperimental results to numerical models.The use of flow visualization in both the prototype and reduced-scale model proved useful inverifying flow patterns predicted by theory and computational fluid dynamic modeling. Thoughseveral techniques were tried before determining that smoke pencils and fogging machines werethe most useful, the influence of relatively small heat sources on the airflow was observed. Thisobservation affected the selection of media used in tracing the flow patterns as well as thevisualization technique employed. Investigating airflow patterns in both the prototype buildingand reduced-scale model was difficult due to the hang time of the media used. Capturing theflow patterns also proved to be a complex task, with hand sketches for various locations withinthe prototype recorded and photo imaging along with hand sketches used in the reduced-scale airmodel. These methods suited the scale of each application, and provided necessary data forcomparison to computer-simulated models.82