Abstract

PRADO HERNANDEZ, Jorge Víctor et al. Simulation of air movement in a venlo-type greenhouse. Terra Latinoam [online]. 2013, vol.31, n.4, pp.325-337. ISSN 2395-8030.

Theoretical approaches and mechanistic models based on energy balance have been employed to study ventilation in greenhouses. These methodologies, however, provide information only on overall ventilation rate and do not provide details of the spatial distribution of the air stream lines. In recent years, it has been shown that mathematical models based on the complete equations of Navier-Stokes model adequately represent ventilation in greenhouses and offer detailed information about spatial distribution of the air mass. Acquiring the permit to use this commercial software is very expensive; therefore, it is important to do research on simplified models in order to reduce research costs. In this study, movement of air was simulated in a Venlo-type greenhouse under different conditions of ventilation using two models: one of them considers the complete Navier-Stokes equations which is called full model, and the other is a Navier-Stokes simplified model in which convective acceleration is not considered in the momentum equation. The full model was solved using the FLUENT software version 11.0 (ANSYS Inc., 2013) and the simplified model was solved numerically in MATLAB. Both methods showed similar results on ventilation rates, but air mass circulation is different in some ventilation scenarios. The simplified method saves more money and time than the full method because its numerical solution can be implemented more easily in medium and high level programming language and because computational times are substantially reduced. To get better results on recirculation zones of the air mass inside a greenhouse, the Navier-Stokes complete model should be considered.

Keywords : natural ventilation; finite element applications; simulation of the ventilation.

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