Predicting Crop Transpiration in a Glasshouse Using Computational Fluid Dynamics (CFD)

Abstract : The aim of this paper is to simulate crop interactions with the climate inside a large glasshouse equipped with continuous roof vents. In this prospect, a set of ornamental species was considered. The modelling approach is based on the resolution of the 2D Navier-Stokes equations with the Boussinesq assumption and a kappa-epsilon closure. Solar and atmospheric radiations were included by solving the Radiative Transfer Equation with the Discrete Ordinate Method and distinguishing short and long wavelength contributions (bi-band model). The crop transpiration was calculated assuming that the canopy may be considered as a porous medium exchanging latent and sensible heat with the ambient environment. The bi-band model was validated under diurnal conditions for a set of external weather conditions (Bournet et al., 2006) and the crop model was validated for lettuce (Boulard and Wang, 2002). In the present study, simulations were conducted under typical summer conditions for eight ornamental species with specific leaf area index values and using the stomatal and aerodynamic resistances reported by Baillle et al. (1994). Results show that the spatial heterogeneity of air velocity and climate inside the greenhouse interferes with plant activity and largely influences crop transpiration. Conversely, the nature of the species itself may strongly interfere with the local climate just above the crop.