...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Reconciling pyroclastic flow and surge: the multiphase physics of pyroclastic density currents
【24h】

Reconciling pyroclastic flow and surge: the multiphase physics of pyroclastic density currents

机译：协调火山碎屑流和涌浪：火山碎屑密度流的多相物理学

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Two end-member types of pyroclastic density current are commonly recognized: pyroclastic surges are dilute currents in which particles are carried in turbulent suspension and pyroclastic flows are highly concentrated flows. We provide scaling relations that unify these end-members and derive a segregation mechanism into basal concentrated flow and overriding dilute cloud based on the Stokes number (S_T), the stability factor (Σ_T) and the dense-dilute condition (D_D). We recognize five types of particle behaviors within a fluid eddy as a function of S_T and Σ_T: (1) particles sediment from the eddy, (2) particles are preferentially settled out during the downward motion of the eddy, but can be carried during its upward motion, (3) particles concentrate on the periphery of the eddy, (4) particles settling can be delayed or 'fast-tracked' as a function of the eddy spatial distribution, and (5) particles remain homogeneously distributed within the eddy. We extend these concepts to a fully turbulent flow by using a prototype of kinetic energy distribution within a full eddy spectrum and demonstrate that the presence of different particle sizes leads to the density stratification of the current. This stratification may favor particle interactions in the basal part of the flow and D_D determines whether the flow is dense or dilute. Using only intrinsic characteristics of the current, our model explains the discontinuous features between pyroclastic flows and surges while conserving the concept of a continuous spectrum of density currents.
机译：通常认为有两种端部碎屑碎屑流：碎屑浪涌是稀流，其中颗粒以湍流悬浮的形式携带，碎屑流为高度集中的流。我们提供了缩放关系，以统一这些末端成员，并基于斯托克斯数（S_T），稳定性因子（Σ_T）和致密稀释条件（D_D）将隔离机制推导为基础集中流动和上覆稀疏云。我们认识到流体涡流中五种类型的颗粒行为是S_T和Σ_T的函数：（1）颗粒从涡流中沉降，（2）颗粒在涡流向下运动时优先沉降，但可以在涡流向下运动时携带向上运动，（3）颗粒集中在涡流的外围，（4）颗粒沉降可以根据涡流空间分布而延迟或“快速跟踪”，并且（5）颗粒在涡流内保持均匀分布。我们通过使用完整涡流谱内的动能分布原型将这些概念扩展到完全湍流，并证明存在不同的粒径会导致电流密度分层。这种分层可能会促进流的基部中的粒子相互作用，并且D_D确定流是稠密的还是稀的。仅使用电流的固有特性，我们的模型解释了火山碎屑流和激增之间的不连续特征，同时保留了密度电流连续谱的概念。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号