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A Sensor for Water Flux in Soil: 2. ‘Line Source’ Instrument
Author(s) -
Byrne G. F.,
Drummond J. E.,
Rose C. W.
Publication year - 1968
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr004i003p00607
Subject(s) - flux (metallurgy) , asymmetry , mechanics , line source , line (geometry) , environmental science , flow (mathematics) , heat flux , measuring instrument , water flow , soil science , temperature measurement , materials science , acoustics , physics , thermodynamics , heat transfer , mathematics , geometry , metallurgy , quantum mechanics
Two sensors are described that measure the flux of water in soil, or the flux of other fluids in any porous medium. The electrical output of such instruments can be of sufficient magnitude that a water flow velocity of 10 −4 cm/sec in soil is readily measured. The flow to be measured causes asymmetry in the temperature field generated by a line source of heat located centrally in the instrument. The temperature difference due to this asymmetry gives rise to the output of the instrument. A theoretical analysis of the temperature field is given for boundary conditions appropriate to each type of sensor. Theoretical and experimental calibrations agreed closely when assumptions in the theory were realized experimentally. The analysis was used to elucidate design principles and their effect on instrument performance.