Numerical analysis of wind microclimatic effects on a plastic greenhouse protected by a windbreak in different seasonal periods
Windbreaks are frequently used to protect greenhouses. Agricultural plastic nets are widely used for the construction of such windbreaks replacing the traditional natural windbreaks formed by trees. When installed against the dominant wind direction at an optimized distance from the greenhouse side walls, windbreaks may reduce wind loads. An additional effect of the provided protection against strong cold winds is the reduction of heat losses during the winter period. However, the effect of windbreaks in situations when cooling is necessary, particularly in cases of low wind speeds during summer period, has not been investigated so far. The present work aims to analyse the energy efficiency and the wind flow around and through an arched-roof greenhouse with two side and one roof opening (windows) in two extreme cases, namely a) a high velocity cold wind causing important heat losses on the greenhouse (closed windows), and b) a low velocity wind speed resulting to buoyancy-driven ventilation in the greenhouse (open windows). In the first case the reduction of heat losses due to the windbreak are explored. In the second case, the possible dissipation of the ventilation airflow and the corresponding temperature variations by the windbreak is investigated. Computational Fluid Dynamics (CFD) numerical simulations are used in the present work.
Giannoulis, A., Mistriotis, A. and Briassoulis, D. 2017. Numerical analysis of wind microclimatic effects on a plastic greenhouse protected by a windbreak in different seasonal periods. Acta Hort. (ISHS) 1170:129-136
CFD analysis, agricultural nets, greenhouses, windbreaks, porosity, energy saving in greenhouses, buoyancy driven ventilation