The model of gravitational flows through a single opening.

We proposed new basic equations and the approximate model for gravitational ventilation through a single openingm which can be incorporated into a ventilation network analysis. The new basic equations are the mass flow balance and the conversion equations of pressure difference and dynamic pressure at an indoor‐outdoor boundary. In order to calculate the mass flow rate by gravitational ventilation using these equations, the following two values at the boundary are required: (1) windward speed, (2) temperature profile. 1. We have shown calculation methods based on the one‐dimensional flow for (1), and used a flow tube model for (2). 2. The neutral pressure level and the inflow‐outflow wind speed can be obtained by steady‐state analysis of basic equations. The coefficients that optimize the calculation results were also shown. 3. We compared the approximate model with the CFD and verified their validity. Finally, the basic characteristics of single‐opening gravitational ventilation were discussed. [ABSTRACT FROM AUTHOR]