Publikationsdatum:
2019
Beschreibung:
Abstract
During volcanic eruptions, model predictions of plume height are limited by the accuracy of entrainment coefficients used in many plume models. Typically, two parameters are used, α and β, which relate the entrained air speed to the jet speed in the axial and cross‐flow directions, respectively. To improve estimates of these parameters, wind tunnel experiments have been conducted for a range of cross wind velocities and turbulence conditions. Measurements are compared directly to computations from the 1D plume model, Plumeria, in the near‐field, bending region of the jet. Entrainment coefficients are determined through regression analysis, demonstrating optimal combinations of effective α and β values. For turbulent conditions, all wind speeds overlapped at a single combination, α = 0.070.06 and β=0.46, which are slightly reduced from standard values. Refined coefficients were used to model plume heights for 1120 historical eruptions. Model accuracy improves modestly in most cases, agreeing to within 3km with observed plume heights. For weak eruptions, uncertainty in field measurements can outweigh the effects of these refinements, illustrating the challenge of applying plume models in practice.
Print ISSN:
2169-9313
Digitale ISSN:
2169-9356
Thema:
Geologie und Paläontologie
,
Physik
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