Using CFD to improve the irrigation strategy for growing ornamental plants inside a greenhouse

Abstract

In order to cope with water scarcity, improved water management should be implemented to reduce water inputs without affecting production. A better quantifying of the heat and water vapour transfers in response to water restriction is thus needed. Distributed climate models, with the addition of transfers through the substrate-plant-atmosphere continuum calculation is a useful tool. However, such models have generally been established for plants grown in well-watered conditions. This study aimed to simulate the transpiration of plants grown in pots and the resulting microclimate in a greenhouse compartment under different irrigation regimes. An experiment was conducted on New Guinea impatiens grown in containers on shelves, in a 100-m2 greenhouse compartment. A 2D transient CFD model was implemented, including a specific sub-model taking into account the water transport in the substrate-plant-atmosphere continuum, as well as the resulting crop interactions with the greenhouse climate for both well-watered and restricted water conditions. The substrate water content was calculated from the water balance. Special care was paid to model the stomatal resistance. Simulation results showed the model ability to correctly predict transpiration, air and leaf temperatures, as well as greenhouse air humidity for both irrigation conditions. Different irrigation scenarios were then tested by reducing the water supply from 100 to 50% of the substrate retention capacity. Simulations allow assessing the model responses on plant transpiration, growing media water potential and climate distribution inside the greenhouse. Consequently, the CFD model could be useful to define an irrigation strategy for a better water input management.