CFD simulation and analysis of a two-sided windcatcher's inlet\outlet geometric shape effect in ventilation flow through a three dimensional room

A windcatcher is a structure fitted on the roof of a building to provide ventilation for the interior space employing wind power; it exhausts the inside stale air to the outside and supplies the outside fresh air into the building interior space working by pressure difference between outside and inside of the building and using ventilation principles of passive stacks and wind tower, respectively. In this paper, the effect of different geometric shapes of inlet/outlet for a two-sided windcatcher on the flow velocity, flow pattern, and flow rate which affect on the ventilation quality through a three-dimensional and typical room fitted with a two-sided windcatcher is observed numerically, applying a commercial computational fluid dynamics (CFD) software package. The standard RANS K-ε CFD method is used in all simulations for three different geometric shapes namely square shape, rectangular shape and circular shape while they have the same area. It is found that the geometric shape of windcatcher's inlet\outlet strongly affects flow pattern, flow rate and flow velocity specially in the living area of the room and there is a relationship between the length/width ratio of the rectangular shape and the ventilation quality