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ISHS Acta Horticulturae 1227: International Symposium on New Technologies for Environment Control, Energy-Saving and Crop Production in Greenhouse and Plant Factory - GreenSys 2017

A mixing-length model of screenhouse ventilation: momentum and energy fluxes

Authors:   I. Seginer, V. Lukyanov, M. Neiman, S. Cohen, M. Teitel, J. Tanny
Keywords:   screenhouse, mixing-length model, momentum and energy profiles
DOI:   10.17660/ActaHortic.2018.1227.29
Abstract:
Screenhouses have recently increased in size to an extent (several ha) that justifies modeling them as infinite structures. Accordingly, a one-dimensional mixing-length model was developed to predict vertical momentum and energy fluxes in flat-roof screenhouses. A further simplifying feature of the model is to treat solar and terrestrial radiation together as a single flux (of net radiation). Data were collected around noon in a large banana screenhouse. Momentum, sensible heat and latent heat flux profiles were determined by eddy covariance, and the flux Bowen ratio was used to close the energy balance. All flux profiles showed the characteristics expected of an infinite screenhouse, in particular, constant fluxes above the screen and discontinuities of net radiation, sensible heat and momentum across the screen. Parameter values extracted by fitting observations to the model include mixing lengths, drag coefficients and extinction coefficients of canopy and screen.

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