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Generation and flow mechanism of powder snow avalanches

粉雪雪崩的产生及流动机制

基本信息

批准号：
09650563
负责人：
FUKUSHIMA Yusuke
金额：
$ 2.3万
依托单位：
Nagaoka University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09650563/
关键词：
powder snow avalanches surface avalanches natural disaster snow drift numerical analysis turbulence model flow dynamics generation mechanism snow engineering 吹雪 K-ε乱流モデル数値シミュレーション固液二相流固気二相流煙型表層雪崩シミュレーションモデル非ブ-シネスク流体 /

项目摘要

In order to get the basic equations for solid-fluid two phase flow, such as snow drift, powder snow avalanches and turbidity currents, the non-Boussinesq k-ε turbulence nodel, refered to as NBKE model, is proposed. NBKE model is appricable to the flow whose density is considerably heavior than the density of ambient fluid. This model consists of the Reynolds equation, mass conservation equations of fluid and solid particles, the equation of the kinetic energy of turbulence and the equaiton of the viscous dissipation rate of turbulence. This model does not assume the Boussinesq approximation and take into account the effect of density viariation not only in the gravity and pressure terms but also in the other term.The experiments on the snow drift in the low temerature wind tunnel were carded out, because the snow drift has basically similar characteristics to the powder snow avalanches. This wind tunnel belongs to Shijo Branch of Snow and Ice Studies, National Research Institute for Ea … More rth Science and Disaster Prevention, Science and Technology Agency. The snow drifts were generated using this apparatus the vertical profiles of wind speed and flux of snow particles for non-equillibrium state. The wind speed was measured by the hot-wire anemometer and the flux of snow particles was meausred by the snow particle counter (SPC).The numerical anslysis of NBKE model were carried out using the given conditions for the wind tunnel experiment. The numerical results explains well the experimental results on wind speed profiles and the snow particle mass flux profiles for the measuring sections. The non-equilibrium snow drift differed from the equilibrium one, especially the profiles of snow flux. These flow is considered to be similar to the transition from snow drift to powder snow avalanches.In order to evaluate the simulation model of powder snow avalanches, the experiment on the inclined suspension thermals of conservatice cases or non-conservative cases were carried out. In case of conservative thermals, the saline water was used. In the case of non-conservative thermals, the mixture of the barium salfate particles and water was used. The flow characteristics such as the variation of the maximum thickness and travel speed were obtained from video-taped record. In addition, the depositional amount of Barium powder and their size distributions are also measured. Using these experimental data, the complex properties of non-conservative inclined thermals were clarified.The generation and flow dynamics of powder snow avalanches are examined by the experiment and numerical analysis based on the fluid dynamical view points and the basic knowledge on these mechanism are clarified. Less

为了得到雪流、粉末雪崩和浊流等固流两相流动的基本方程，提出了非boussinesq k-ε湍流模型，简称NBKE模型。NBKE模型适用于密度比周围流体密度大得多的流体。该模型由雷诺方程、流体和固体颗粒的质量守恒方程、湍流动能方程和湍流粘性耗散率方程组成。该模型不采用Boussinesq近似，并考虑了密度变化的影响，不仅在重力和压力项，而且在其他项。在低温风洞中进行的雪漂移实验进行了梳理，因为雪漂移与粉末雪崩具有基本相似的特性。该风洞隶属于科学技术厅北方科学与防灾研究所冰雪研究所石城分所。利用该装置生成了非平衡状态下的风速和雪粒通量的垂直剖面图。用热线风速仪测量风速，用雪粒计数器（SPC）测量雪粒通量。在给定风洞试验条件下，对NBKE模型进行了数值分析。数值计算结果较好地解释了测区风速廓线和雪粒子质量通量廓线的实验结果。非平衡雪流与平衡雪流不同，特别是雪通量的分布。这些流动被认为类似于从雪漂到粉雪雪崩的转变。为了评价粉末雪崩的模拟模型，进行了保守和非保守两种情况下的倾斜悬浮热实验。在保守热的情况下，使用盐水。在非保守热的情况下，使用盐酸钡颗粒和水的混合物。通过录像记录得到了最大厚度和移动速度的变化等流动特性。此外，还测量了钡粉的沉积量和粒径分布。利用这些实验数据，阐明了非保守倾斜热源的复杂性质。从流体力学的观点出发，通过实验和数值分析研究了粉末雪崩的产生和流动动力学，阐明了粉末雪崩形成机理的基本知识。少