(J. of the Society of
Agricultural Structures, Japan, 30(2), 133-142, 2009)
Numerical Analysis on
Microclimate inside Four Single-Span Greenhouses under
Various Wind Speeds
and Directions using CFD
Digui YANG, Kazuhiro NAKANO,
Daisuke TERANO, Haijun YAN, Shintaroh OHASHI and Qingyun CHEN
Summary
The microclimate inside a group of four single-span greenhouses, with a narrow space between two adjacent greenhouses, was numerically analyzed using a Computational Fluid Dynamics (CFD) package under different wind conditions. First, three-dimensional simulations were validated through experimental measurements. Good agreement was obtained between the experimental and numerical results. Second, simulations were carried out under steady-state conditions. The air exchange rate and temperature distribution under various wind speeds and directions were analyzed based on the numerical results.The results showed: a) with the same outside wind speed and direction, the air exchange rate of the greenhouses was strongly affected by their relative location to the wind direction according to whether they were windward or leeward; b) there was a shelter effect for the air temperature inside greenhouses that were leeward to the wind direction; and c) the buoyancy effect played an important role in the calculation of the air exchange rate of greenhouses when the outside wind speed was lower than 1 m/s, but the air exchange rate had almost a linear relation to the outside wind speed when it was higher than 2 m/s, which meant the buoyancy effect resulting from the temperature difference was negligible.