Effects of side vents and span numbers on wind-induced natural ventilation of a gothic multi-span greenhouse

In this paper, the effects of wind speed, side ventilators and span numbers on gothic type multi-span greenhouse natural ventilation were studied by numerical simulation using the Computational Fluid Dynamics (CFD) approach. The realizable k-epsilon model was used for the turbulence model in the simulations. The results showed that the maximum greenhouse ventilation rate was achieved when both side and roof vents were used for ventilation. Without the existence of buoyancy effect in the computations, it was found that the ventilation rate increased linearly with the external wind speed in all the cases studied. The ratio of the opening of the ventilator area to the greenhouse floor area, 9.6%, was found to be small compared to the recommended ratios of 15-25%. The results showed that a significant reduction in ventilation rate was determined as the number of spans was increased and an exponential decay explained the relationship between the ventilation rate and the number of spans.