The Entrainment Rate of Non-Boussinesq Hazardous Geophysical Gas-Particle Flows: An Experimental Model With Application to Pyroclastic Density Currents
Por:
Dellino P., Dioguardi F., Doronzo D.M., Mele D.
Publicada:
1 ene 2019
Resumen:
The entrainment rate of pyroclastic density currents is investigated by large-scale experiments. The ground flows are initiated by the impact on the terrain of a dense gas-particle fountain issuing from a cylindrical conduit, similarly to natural volcanic events. On impact, the excess density with respect to the surrounding atmosphere was up to 11.6 kg/m3, making the currents non-Boussinesq. A power law model of the entrainment rate is developed, which is similar to that proposed for snow avalanches by Ancey (2004, https://doi.org/10.1029/2003JF000052) and is verified for the Richardson's number range between 0.25 and 5.95. Rapid changes of the entrainment are caused by (i) strong accelerations at the fountain impact on the ground; (ii) break in slope; and (iii) topographic obstacles. Such changes, together with the sedimentation rate, influence flow mobility. The use of the power law is suggested for modeling the motion of unsteady hazardous geophysical mass flows such as pyroclastic density currents and snow avalanches. ©2019. American Geophysical Union. All Rights Reserved.
Filiaciones:
Dellino P.:
Dipartimento di Scienze della Terra e Geoambientali, Università di Bari, Bari, Italy
Dioguardi F.:
British Geological Survey, The Lyell Centre, Edinburgh, United Kingdom
Doronzo D.M.:
Institute of Earth Sciences “Jaume Almera,” ICTJA, CSIC, Group of Volcanology, SIMGEO UB-CSIC, Barcelona, Spain
Mele D.:
Dipartimento di Scienze della Terra e Geoambientali, Università di Bari, Bari, Italy
All Open Access; Green
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