| Abstract: | Volcanic plumes are often studied using one-dimensional analytical models, which use an empirical entrainment ratio to close the equations. Although this ratio is typically treated as constant, its value near the vent is significantly reduced due to flow development and overpressured conditions. To improve the accuracy of these models, a series of experiments was performed using particle image velocimetry, a high-accuracy, full-field velocity measurement technique. Experiments considered a high-speed jet with Reynolds numbers up to 467,000 and exit pressures up to 2.93 times atmospheric. Exit gas densities were also varied from 0.18 to 1.4 times that of air. The measured velocity was integrated to determine entrainment directly. For jets with exit pressures near atmospheric, entrainment was approximately 30% less than the fully developed level at 20 diameters from the exit. At pressures nearly three times that of the atmosphere, entrainment was 60% less. These results were introduced into Plumeria, a one-dimensional plume model, to examine the impact of reduced entrainment. The maximum column height was only slightly modified, but the critical radius for collapse was significantly reduced, decreasing by nearly a factor of two at moderate eruptive pressures. |
| Genre: | Article |
| ProdID: | 70041416 |
| Citation Author: | Saffaraval, Farhad; Solovitz, Stephen A.; Ogden, Darcy, E.; Mastin, Larry G. |
| Citation Contributing Office: | Cascade Volcanoes Observatory |
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| Citation Issue: | B05209 |
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| Citation Language: | English |
| Citation Larger Work Title: | Journal of Geophysical Research |
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| Citation Number Of Pages: | 13 |
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| Citation Phsyical Description: | 13 p. |
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| Citation Publisher: | American Geophysical Union |
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| Citation Search Results Text: | Impact of reduced near-field entrainment of overpressured volcanic jets on plume development; 2012; Article; Journal; Journal of Geophysical Research; Saffaraval, Farhad; Solovitz, Stephen A.; Ogden, Darcy, E.; Mastin, Larry G. |
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| Citation Volume: | 117 |
| Citation Year: | 2012 |
| Type: | citation/reference |
| Text: | Impact of reduced near-field entrainment of overpressured volcanic jets on plume development; 2012; Article; Journal; Journal of Geophysical Research; Saffaraval, Farhad; Solovitz, Stephen A.; Ogden, Darcy, E.; Mastin, Larry G. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| URL (DIGITAL OBJECT IDENTIFIER): | http://dx.doi.org/10.1029/2011JB008862 |
| Date Other: | Mon, 10 Dec 2012 00:00 -0600 |
| Publisher: | American Geophysical Union |
