A model for wet aggregation of ash particles in volcanic plumes and clouds: 1. Theoretical formulation
A model for wet aggregation of ash particles in volcanic plumes and clouds: 1. Theoretical formulation
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DOI：
10.1029/2009jb007175
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发表时间：
2010-09-01
影响因子：
3.9
通讯作者：
Macedonio, Giovanni
中科院分区：
文献类型：
--
作者：
Costa, Antonio;Folch, Arnau;Macedonio, Giovanni
我们开发了一个模型来描述火山灰聚集在火山羽。该模型是基于经典的Smoluchowski方程的解决方案，通过引入一个相似性变量和分形关系的聚集体中的初级颗粒的数量。所考虑的碰撞频率函数考虑了不同的聚集机制，如布朗运动、环境流体剪切和差异沉降。虽然模型公式是通用的，这里只考虑与水的存在有关的粘附效率。然而，液态水和冰的不同的结合效果被识别。所提出的方法代表了第一个妥协之间的完整描述的聚集过程，并需要减少计算所需的时间来解决完整的Smoluchowski方程。我们还进行了参数化研究的主要模型参数和估计凝聚内核和时间尺度的聚合过程中的简化条件下的兴趣在火山学。进一步的分析和应用，真实的喷发中提出的配套文件由Folch等人。
We develop a model to describe ash aggregates in a volcanic plume. The model is based on a solution of the classical Smoluchowski equation, obtained by introducing a similarity variable and a fractal relationship for the number of primary particles in an aggregate. The considered collision frequency function accounts for different mechanisms of aggregation, such as Brownian motion, ambient fluid shear, and differential sedimentation. Although model formulation is general, here only sticking efficiency related to the presence of water is considered. However, the different binding effect of liquid water and ice is discerned. The proposed approach represents a first compromise between the full description of the aggregation process and the need to decrease the computational time necessary for solving the full Smoluchowski equation. We also perform a parametric study on the main model parameters and estimate coagulation kernels and timescales of the aggregation process under simplified conditions of interest in volcanology. Further analyses and applications to real eruptions are presented in the companion paper by Folch et al.