Flow Network Model based on Power Balance as Applied to Cross-Ventilation

This paper reviews the flow network model based on power balance as applied to wind-induced cross ventilation in a residential building. The characteristics of wind-induced cross-ventilation with open windows in buildings are different from those of air infiltration through cracks in walls. The features of the velocity and pressure distributions are apparently different. In cross-ventilation, it seems that a kind of stream tube is formed through the building. A large part of the dynamic pressure generated at the opening is preserved within the room, and a major part of the preserved energy is directly convected outside the room. The preservation of energy is reflected as a decrease in the value of the total pressure loss coefficient, in a consistent manner in the energy-losing process. In this paper, a flow network model, based on the power balance model, which considers preservation of dynamic pressure and energy loss evaluation, is introduced. The power balance model well describes the energy-loss process of diverging and converging flows. There seems to be a large possibility that the model introduced works well in predicting the air flow rate of wind-induced cross-ventilation in a residential building compared to the usual models based on the extended Bernoulli's equation within a stream tube (a one-dimensional energy equation)