The Heat of the Flow: Thermal Equilibrium in Gravitational Mass Flows

Oxford

Wiley

2018

11,219-11,226

Sonderdruck

203676

Geophysical Research Letters ; Jrg. 45 ; 20 (2018) , 11,219-11,226

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.
Key Points: The temperature evolution of a flowing geomaterial was analytically modeled and measured in laboratory drum experiments ; We found thermal equilibrium as a result of frictional energy dissipation compensated by ambient cooling ; Material properties of the gravitational mass flow were determined from temperature measurements Supporting Information: