Articles
VALIDATION OF CFD SIMULATION OF AIRFLOW FROM AN AIR CIRCULATOR ABOVE CROPS
Article number
1008_28
Pages
213 – 220
Language
English
Abstract
Computational fluid dynamics is a useful tool for investigating the effects of positioning of air circulators relative to the profile of airflow in a greenhouse.
This study investigates the influence of crop rows on the air circulation, and examines the relevant settings, including the heterogeneous distribution of the leaf area density of a crop, to predict of the airflow generated by an air circulator.
Measurements showed that in the absence of crop rows, the air velocity exceeded 0.15 m s-1 in 73.4% of the grids, but in the presence of crop rows, the percentage decreased to 53.5-61.2%. The airflow from the air circulator was slightly stagnant between crop rows, though the profiles of the air velocity above the canopy were indistinguishable from those where there was no crop canopy.
Results of the validation indicated that the grid size was the most significant factor for predicting the airflow generated by an air circulator, as compared to the time-step size and turbulence model used.
There was no disparity between the calculated air velocity profiles when the crop rows were treated as a porous medium with a uniform versus a heterogeneous leaf area density.
The distribution of the simulated air velocity was in qualitative agreement with the measurements, when proper settings were used.
The relative stagnancy of the airflow due to the crop rows agreed with the measurements in terms of the percentage of grids in which an air velocity above 0.15 m s-1 was measured.
This study investigates the influence of crop rows on the air circulation, and examines the relevant settings, including the heterogeneous distribution of the leaf area density of a crop, to predict of the airflow generated by an air circulator.
Measurements showed that in the absence of crop rows, the air velocity exceeded 0.15 m s-1 in 73.4% of the grids, but in the presence of crop rows, the percentage decreased to 53.5-61.2%. The airflow from the air circulator was slightly stagnant between crop rows, though the profiles of the air velocity above the canopy were indistinguishable from those where there was no crop canopy.
Results of the validation indicated that the grid size was the most significant factor for predicting the airflow generated by an air circulator, as compared to the time-step size and turbulence model used.
There was no disparity between the calculated air velocity profiles when the crop rows were treated as a porous medium with a uniform versus a heterogeneous leaf area density.
The distribution of the simulated air velocity was in qualitative agreement with the measurements, when proper settings were used.
The relative stagnancy of the airflow due to the crop rows agreed with the measurements in terms of the percentage of grids in which an air velocity above 0.15 m s-1 was measured.
Authors
T. Kuroyanagi
Keywords
air movement, greenhouse, fan, leaf density, turbulence model
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