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Estimating Thermal Diffusivity Near the Soil Surface Using Laplace Transform: Uniform Initial Conditions
Author(s) -
Asrar G.,
Kanemasu E. T.
Publication year - 1983
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1983.03615995004700030001x
Subject(s) - laplace transform , thermal diffusivity , inverse laplace transform , thermal conduction , laplace transform applied to differential equations , heat equation , laplace's equation , materials science , thermal , boundary value problem , mathematics , thermal conductivity , porosity , mechanics , mathematical analysis , thermodynamics , physics , composite material
A simplified method based on the numerical integration of the Laplace transform of the one dimensional heat conduction equation in porous media was used to estimate the thermal diffusivity near the surface. The method is based on the analytical solution of the equation of heat conduction and accepts any functional relationship that realistically describes the surface soil temperature as a boundary condition. An optimization scheme was suggested for selecting proper values of Laplace transform parameter s based on maximum duration of the experiment. The method was used to compute thermal diffusivities of two different soil types for a wide range of soil moisture and temperature conditions. Thermal conductivities for each soil were calculated using the computed diffusivities and heat capacities. A comparison of the conductivities estimated with the Laplace transform and the measured values by a transient method showed good agreements between the two methods. A similar comparison between the Laplace transform and the DeVries' model showed significant differences between the two methods.