Wind tunnel study of the interaction of two or three side-by-side pipe-framed greenhouses on wind pressure coefficients

More than two identical pipe-framed greenhouses (referred to as "pipe houses" hereafter) are often arranged in parallel. The wind pressure distributions on the pipe houses are significantly affected by the distance d _p between them. This article investigates the effect of d _p on the distribution of wind pressure coefficients C _p on two or three pipe houses arranged in parallel, based on a wind tunnel experiment using 1:20 scale models of a typical pipe house. Focus was on a wind direction perpendicular to the ridgeline. The distance d _p varied from 0.25H to 6H, with H being the ridge height of the pipe house. The results indicate that the C _p distribution on the windward side of the first pipe house was similar to that for an isolated pipe house, while the C _p values on the roof and leeward wall were dependent on d _p. On the other hand, the C _p values on the second and third pipe houses were generally negative and significantly affected by d _p, in particular on the windward wall and roof. Very high suctions were induced on the leeward roof of the second pipe house near the ridge when the distance d _p was small. The suctions may be induced by the second separation of the reattached flow on the windward roof at the location of the ridge. The local drag and lift coefficients, C _do and C _l, on the central cross-section were also computed from the C _p distribution. The influence of the adjacent pipe houses on the C _D was significant, while the C _l was less sensitive to d _p.