Numerical simulation of airflow pattern and calculation of crop transpiration in plastic greenhouse

In order to analyze the airflow pattern and crop evapotranspiration in the plastic greenhouse. Based on computational fluid dynamics simulation, the natural ventilation process in the common plastic greenhouse in East China was performed, and the relationship between the inside ventilation rate and outside wind rate was also established. The aim of the simulation was to investigate the airflow pattern inside the greenhouse and determinate the ventilation parameter related to transpiration. A simple model based on the energy balance model and the turbulent diffusion model had been developed. The model was verified with a non-stress crop with only the inside measured air temperature and outside climate data. The simulated greenhouse crop transpiration was compared with the measurement data and they were found to agree well with each other. Moreover, the correlation determination coefficient between the simulated and measured daily transpiration was 0.776, which of accumulated transpiration was 0.998. While the standard error and the maximum absolute deviation between the simulated and measured accumulated transpiration were 1.16 mm and 4.82 mm. Results show that the equation established need less parameters and the wind parameters inquired were suitable for ordinary greenhouses. This study could meet the needs of crop water management, greenhouse design, and regional water management.