Abstract
Turbulence phenomena created around a greenhouse due to different wind loads are key factors in its structural design and significantly affect the ventilation rates through its side and roof openings. Using the turbulence models of ANSYS FLUENT software to investigate the airflow around an arched-roof-greenhouse-shaped obstacle placed inside a wind tunnel was the aim of this study. Velocity and pressure areas around the obstacle were examined by selecting three different turbulence models (Standard, RNG and Realizable k–ε models) under three different airflow entry velocities (0.34, 1.00 and 10.00 m s−1) in the wind tunnel. All k–ε models showed that when the air velocity was intensified, the airflow was identified as turbulent. The horizontal velocity profile predicted more accurately the presence of vortices in contrast with the vector sum of the perpendicular velocity components. Vortices were formed upstream, above the roof and downstream of the obstacle, and the applied models showed that when airflow velocity increases, the size of the upstream vortex decreases. Finally, there was a strong indication from the modeling results that the vortex on the roof of the obstacle was an extension of the vortex that was created downstream.
Highlights
Studying the airflow around and over an agricultural structure could possibly resolve substantial issues related to the proper functioning of these structures
The equations that govern the dynamic behavior of fluids are the Navier–Stokes (N–S) equations, which are the basis of modeling through computational fluid dynamics [4,5,6]
An air tunnel experiment was conducted for better validation of the used models, and the results showed that in all cases the maximum speeds appeared at the top of the construction
Summary
Studying the airflow around and over an agricultural structure (greenhouse, livestock unit, etc.) could possibly resolve substantial issues related to the proper functioning of these structures. Ventilation affects temperature, humidity and CO2 concentration, and in livestock buildings it is important for minimizing the concentrations of harmful gases (NH3 , CO2 , CH4 , N2 O, etc.) that have adverse effects on the wellbeing of animal and workers [1,2,3,4]. Most research efforts concentrated on studying the airflow through modeling using computational fluid mechanics for openings in specific locations, mainly on the side surfaces of greenhouses. These openings can cause damage to the materials of the building if the wind is stronger than the air speed limit set by the manufacturer.
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