[论文解读] A multi-phase thermo-mechanical model for rock-ice avalanche

Shiva P. Pudasaini|arXiv (Cornell University)|Apr 9, 2024

Landslides and related hazards被引用 10

一句话总结

论文开发了一种新颖、基于物理的多相（岩石-冰-流体）热力机械模型用于岩石-冰雪崩，推导出一般温度方程和统一的融冰公式，将热传导、冰融化、卷入和跨岩石、冰、流体相的质量/动量交换耦合起来。

ABSTRACT

We propose a novel multi-phase thermo-mechanical rock-ice avalanche model. It considers rock, ice and fluid; includes rigorously derived ice melt rate, melting efficiency dependent fluid production rate and a general temperature equation. It explains advection-diffusion of heat including heat exchange across the avalanche, basal heat conduction, production and loss of heat due to frictional shearing and changing temperature, and temperature enhancement due to entrainment. Temperature equation couples rates of thermal conductivity and temperature. Ice melt intensity determines these rates as mixture conductivity evolves, characterizing thermo-mechanical processes. The model includes interfacial mass and momentum exchanges and mass and momentum productions due to entrainment. The latter significantly changes the state of temperature; yet, the former characterizes the rock-ice avalanche. Phase mass and momentum balances and temperature are coupled. New model offers the first-ever complete dynamical solution for rock-ice avalanche with changing temperature and ice melting. We develop an advection-diffusion-decay-source model and its analytical solutions providing novel understanding of temperature evolution. The 2021 Chamoli event simulations with r$.$avaflow (https://www.landslidemodels.org/r.avaflow/) illustrate the functionality of thermo-mechanical rock-ice avalanche model. Four scenarios are considered: variations in ice-melt-efficiency; fraction of ice; ice and rock frictions; governing the process of melting, flow transformation, spreading and mobility. Ice melting designates the motion and explains the rock-ice avalanche mobility: a phenomenal thermo-mechanical play. Essentially different controls of ice and rock frictions on the state of flow mobility are revealed, explaining complex thermo-mechanical processes. This provides a useful method for practitioners and engineers in solving problems associated with rock-ice avalanches.

研究动机与目标

• 需要将岩石-冰雪崩建模为具有温度变化的多相系统的动机。
• 推导出用于雪崩主体的通用、动态演化的温度方程。
• 将冰融化、基底卷入以及相之间的质量/动量交换纳入统一模型。
• 提出便于实际仿真的热力机械过程的深度平均闭包。

提出的方法

• 将多相质量流动框架扩展为包含岩石、冰和流体作为三种成分。
• 推导并对一般温度方程进行深度平均，包含热产生与损失项、边界热交换和基底传导。
• 将摩擦性剪切加热和冰融化耗散项以深度平均闭包形式给出。
• 推导两种冰融化机制（摩擦加热和温度变化驱动的融化），并提出总融化率的统一线性混合形式。
• 纳入内部质量与动量交换、床面的卷入，以及相动态与温度演化之间的耦合。

实验结果

研究问题

• RQ1 岩石-冰雪崩如何被建模为真正的三相系统并包含温度演化？
• RQ2 雪崩质量的通用、动态演化温度方程是什么，冰融化如何反馈到动力学中？
• RQ3 摩擦加热、边界热交换和卷入如何影响冰融化速率及整体热力机械状态？
• RQ4 如何将冰融化速率统一并嵌入深度平均的质量和动量守恒中？
• RQ5 模拟温度变化的岩石-冰雪崩所需的关键热力机械闭包是什么？

主要发现

• 一种新颖的多相热力机械模型，将岩石、冰和流体耦合在一起，并具备动态演化的温度方程。
• 一种用于对流-扩散热传输的深度平均框架，包含边界热交换和基底传导。
• 严格推导的摩擦热产生项及相关冰融化速率，以及与剪切相关的正式融化耗散机制。
• 通过线性混合参数，将摩擦加热与温度变动效应结合的统一冰融化速率。
• 证明相质量/动量平衡与温度方程之间的强耦合，使岩石-冰雪崩仿真具备完整的动力解。