Alternative solution proposal to improve the air change in light shafts based on flaps

Outdoor air change qualifies the air that enters into the buildings. The outdoor air moves freely along the urban mesh favoured by the wind forces and stresses. Buildings, trees and other constructions alter the natural air flow pattern inside the cities, creating stagnated air masses in those wind-protected regions. Some outdoor spaces such as light shafts and confined light shafts inhibit the correct exchange of the stagnated air with fresh air coming from the outskirts and suburban areas. 
The research proposed based on computational simulations tries to evaluate the susceptibility of several light shafts to infer the air change of their air by placing flaps close to their upper opening, where fresh air gets into exhausting the stagnated one. The flap is located over the opening aims to change the air flow pattern inside the light shaft by using Venturi effect partially sucking the stagnated air. 
Results show that in the proposed cases the air velocity distribution is changed along the light shaft, affecting the air flow related to the reference case. The air flow through the opening increases ten times when the flap is placed. Nevertheless, the impact of the flap in the air change is negligible because the mean age of the air inside the light shaft does not decrease. It would be necessary to propose new flap models, which will affect the distribution of the air inside light shafts to improve the air change.