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The Heat of the Flow: Thermal Equilibrium in Gravitational Mass Flows
Author(s) -
Fischer JanThomas,
Kaitna Roland,
Heil Kilian,
Reiweger Ingrid
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl079585
Subject(s) - mechanics , snow , thermal , heat transfer , energy balance , flow (mathematics) , dissipation , thermal energy , materials science , thermodynamics , geology , physics , meteorology
Abstract Flow behavior and mobility of gravitational mass flows such as rapid‐moving landslides, ice‐rock avalanches, or snow avalanches strongly depend on the material temperature. Flow temperature dependence is particularly pronounced for materials with high homologous temperatures, such as snow or ice under natural conditions. The interplay between mechanisms driving the temperature evolution in flowing geomaterials remain largely unknown. Here we present laboratory experiments in a rotating drum, measuring the temperature evolution of steadily flowing snow at ambient temperatures below freezing. After initial heating the flow reaches thermal equilibrium. To describe the thermal energy balance, we derive an analytical model, taking into account frictional energy dissipation and heat exchange with the ambient medium. The model accurately captures the measured temperature evolution and predicts the observed thermal equilibrium, where ambient cooling compensates frictional heating. It allows to determine heat transfer coefficients and total shear stresses of the flowing material based on measured temperatures.