چکیده:
The natural ventilation is an easy way to exchange the indoor polluted warm air with outdoor fresh air. The wind power injects outdoor fresh air into the building. A good indoor air current and subsequently a proper exhaust depend on the openings’ conditions and their situations. A serious architectural question is under what conditions of the openings the wind-cross ventilation can be effective, and the required indoor air current in the enclosure is established. The purpose of this article is analyzing the conditions of indoor airflow in an analytical architectural model to upgrade the natural ventilation by focusing on opposite opening’s conditions. This research considers some wind driven ventilation manner with respect to openings circumstances in an assumed cubic model. The research method includes a numerical simulation using a validated computational fluid dynamics (CFD) model. It investigates and compares the performances of different models of airflow currents in a natural ventilation process and subsequently the indoor airflow paths, under the different conditions of the openings in a fixed boundary condition model; the simulations are performed in an assumed model (a 6×6×6m cubic building with just 2 opposite openings in stationary walls as boundaries of the model) by using Gambit and Fluent software. With an analytical method (using Fluent) the gathered data would be analyzed. Finally the results are presented and generalized: the results demonstrate that whatever the wind speed is, the indoor airflow condition depends on the situations of the openings. It means that the quality of wind- driven cross ventilation and its path is not depended on the wind speed. Besides for establishing proper natural ventilation, the opposite windows must not be installed in front of each other, or in the same level.
خلاصه ماشینی:
Natural Ventilation: Analysis of Indoor Airflow in an Assumed Cubic Building with Opposite Openings by CFD Investigations Omid Rahaei1* 1Assistant Professor of Architecture, Department of Architecture, Shahid Rajaei Teacher Training University, Tehran, Iran Received 16 March 2015; Revised 11 October 2015; Accepted 13 October 2015 The natural ventilation is an easy way to exchange the indoor polluted warm air with outdoor fresh air.
It investigates and compares the performances of different models of airflow currents in a natural ventilation process and subsequently the indoor airflow paths, under the different conditions of the openings in a fixed boundary condition model; the simulations are performed in an assumed model (a 6×6×6m cubic building with just 2 opposite openings in stationary walls as boundaries of the model) by using Gambit and Fluent software.
Following the the simulations and the above-mentioned analyzes (for the cases of A, B, & C in 2d stances), following the conditions of indoor airflows, case C is refused; because the natural ventilation in this case is violence, air speed is so slow, and the indoor airflow’s stance especially in people levels is self-circulating.
Following the CFD models, configuration of fig 13 that the outdoor wind is blowing toward the upper opening (windward), is the best condition to establish an overall indoor airflow by natural ventilation (10% Porosity in each 2 opposite walls; the side walls and roof have no Porosity).