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Moisture transfer in free and forced convection
Author(s) -
Crawford T. V.
Publication year - 1965
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49709138704
Subject(s) - turbulence , convection , combined forced and natural convection , forced convection , thermodynamics , richardson number , mechanics , moisture , environmental science , meteorology , natural convection , physics , atmospheric sciences
The vertical transfer of moisture is examined under conditions where the Richardson number varies from − 2.5 to + 2.9. The use of a non‐dimensional evaporative flux, similar to Priestley's (1959) non‐dimensional sensible heat flux, and extensive data from the Davis lysimeter field show a smooth transition from forced to free convection. An equation for this transitional regime of mixed convection is derived by dimensional analysis and fitted to the data for different Richardson number ranges. A free convection interpretation of the data for −2.5 < Ri < −0.025 gives a proportionality constant of 1.40. In stable conditions, the turbulent transfers are shown to decrease rapidly with increasing + Ri and this behaviour is consistent with some estimates of the initiation of decay of turbulence.