Inter-comparison of three-dimensional models of volcanic plumes
Inter-comparison of three-dimensional models of volcanic plumes
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DOI：
10.1016/j.jvolgeores.2016.06.011
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发表时间：
2016-10-15
影响因子：
2.9
通讯作者：
Denby, L. C.
中科院分区：
文献类型：
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作者：
Suzuki, Y. J.;Costa, A.;Denby, L. C.
我们进行了一个比较研究的三维模型的火山羽。为两种类型的喷发提供了一套共同的火山学输入参数和气象条件，分别代表弱喷发柱和强喷发柱。从不同的模式，我们比较了最大羽流高度，中性浮力水平（羽流密度等于大气），和水平的伞云的最大径向扩散。我们还比较了垂直配置文件的喷发柱属性，集成跨横截面的羽流（积分变量）。虽然模型使用不同的数值程序和亚网格湍流和粒子动力学的处理，相互比较表明定性一致的结果。在弱羽流情况下（质量喷发率1.5 x 10（6）kg s（-1）），羽流特性的垂直剖面（例如，垂直速度，温度）是相似的模式，特别是在浮力羽流区。模拟的最大高度之间的变化类似于20%，而中性浮力水平和最大径向扩展水平的变化类似于10%。时间平均的三维（3D）流场表明，在浮力羽流区域的有效夹带系数约为0.1，在射流区域的值要低得多，这是与小规模的实验室实验的结果是一致的。另一方面，强羽流情况（质量喷发率1.5 x 10（9）kg s（-1））显示不同模型预测的垂直羽流剖面变化较大。我们的分析表明，在强大的羽流不稳定的流动动力学增强的差异，制定和数值解的模型。这一点在羽流的过冲顶部尤其明显，它延伸了最大羽流高度的很大一部分（类似于1/8）。尽管如此，扩展水平和中性浮力水平的总体可变性类似于20%，而最大高度的可变性类似于10%。这项相互比较研究突出了3D火山羽流模型的不同功能，并确定了弱羽流和强羽流的关键特征，包括射流稳定性，夹带效率和颗粒非平衡的作用，值得在现场，实验室和数值研究中进行进一步研究。(C)2016爱思唯尔B. V.保留所有权利。
We performed an inter-comparison study of three-dimensional models of volcanic plumes. A set of common volcanological input parameters and meteorological conditions were provided for two kinds of eruptions, representing a weak and a strong eruption column. From the different models, we compared the maximum plume height, neutral buoyancy level (where plume density equals that of the atmosphere), and level of maximum radial spreading of the umbrella cloud. We also compared the vertical profiles of eruption column properties, integrated across cross sections of the plume (integral variables). Although the models use different numerical procedures and treatments of subgrid turbulence and particle dynamics, the inter-comparison shows qualitatively consistent results. In the weak plume case (mass eruption rate 1.5 x 10(6) kg s(-1)), the vertical profiles of plume properties (e.g., vertical velocity, temperature) are similar among models, especially in the buoyant plume region. Variability among the simulated maximum heights is similar to 20%, whereas neutral buoyancy level and level of maximum radial spreading vary by similar to 10%. Time-averaging of the three-dimensional (3D) flow fields indicates an effective entrainment coefficient around 0.1 in the buoyant plume region, with much lower values in the jet region, which is consistent with findings of smallscale laboratory experiments. On the other hand, the strong plume case (mass eruption rate 1.5 x 10(9) kg s(-1)) shows greater variability in the vertical plume profiles predicted by the different models. Our analysis suggests that the unstable flow dynamics in the strong plume enhances differences in the formulation and numerical solution of the models. This is especially evident in the overshooting top of the plume, which extends a significant portion (similar to 1/8) of the maximum plume height. Nonetheless, overall variability in the spreading level and neutral buoyancy level is similar to 20%, whereas that of maximum height is similar to 10%. This inter-comparison study has highlighted the different capabilities of 3D volcanic plume models, and identified key features of weak and strong plumes, including the roles of jet stability, entrainment efficiency, and particle non-equilibrium, which deserve future investigation in field, laboratory, and numerical studies. (C) 2016 Elsevier B.V. All rights reserved.