Measurement and CFD simulation of microclimate characteristics and transpiration of an Impatiens pot plant crop in a greenhouse

Numerical simulations of the microclimate inside a greenhouse canopy were validated. Experiments were conducted inside a 100 m2 greenhouse compartment with a shading screen and potted Impatiens plants grown on benches. The greenhouse was equipped with a set of sensors, including a sonic and hot-bulb anemometers, thermocouples, air-humidity/temperature probes and balances.Thermal and water vapour exchanges between the crop and its environment were studied using 2D simulations of the microclimate carried out at a daily time scale within a calculation domain reduced to a parallelepiped, including the plants. The Navier–Stokes equations were solved using the standard k − ε turbulence model. A crop submodel which considers the crop as a porous medium and adds specific source terms for latent and sensible heat transfers was used. Two contrasting days with relatively high and low solar insulations were considered. For both cases, the computational fluid dynamics (CFD) model showed its ability to simulate the air temperature inside the canopy as well as the vertical distribution of the leaf temperatures throughout the day. It predicted the decrease of leaf temperature from the top to the bottom of the crop with good accuracy. It also provided a good estimation for the trend of transpiration rate throughout the day (coefficients of determination > 0.92). Differences between the measured and simulated integrated transpiration rates over 24 h-periods remained < 15%. Consequently, the model could be useful to assess the water requirements of a crop for the purpose of adapting irrigation management to meet plant needs.

► The crop inside a greenhouse interacts with the local climate through coupled mechanisms. ► CFD can be used to assess momentum and energy transfers induced by the canopy. ► CFD makes it possible to predict the evolution of the transpiration rate and leaf temperatures. ► CFD could be a good tool to assess water requirements and adapt an irrigation strategy.