A technical note on simplified modeling of turbulent mixing in wind-driven single sided ventilation

Single sided ventilation is a commonly used room natural ventilation strategy. Small, single occupant offices, often use single sided ventilation through a single opening (SS1). In most multistory buildings, the ratio between building façade and SS1 window opening area is 0.1% or less. In these cases, wind driven SS1 flows are caused by entrainment of room air that contacts outdoor airflow along the building opening plane. The turbulent mixing layer that develops in this region is central to the room airflow development process. The existing theoretical analysis of these flows was developed in 1977 and preceded several experimental studies of turbulent mixing layers that revealed new flow features that impact the resulting airflow estimate. This technical note presents a simple analytic calculation of turbulent mixing in SS1 flows that incorporates these developments. The proposed approach can predict the bulk ventilation flow rates measured in wind tunnel studies with an over prediction of 21%, a significant improvement over the existing analysis that resulted in an average under-prediction of 70%.