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arXiv 1809.01003cond-mat.stat-mechphysics.comp-ph
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随机介质稳态和瞬态热传导的均匀化随机分析

A Stochastic Analysis of Steady and Transient Heat Conduction in Random Media Using a Homogenization Approach

Zhijie Xu

摘要:

基于均匀化方法,提出了一维稳态和瞬态热传导问题的一种新的随机分析方法。导热系数被假定为一个随机场K,它由一个总数为N的随机变量组成。稳态解和瞬态解T都表示为均匀化解及其空间导数,其中均匀化解是通过求解具有有效导热系数的均匀化方程获得的。对于由同分布(i.i.d)随机变量组成的K场,可以解析地得到随机解的均值和方差。T的均值和方差仅依赖于这些独立同分布变量的均值和方差,而不依赖于独立同分布变量的概率分布函数的特定形式。温度场T的变化可以分为两种贡献:系综贡献(通过均匀化温度)和构型贡献(通过不同构型)。构型的贡献被证明是成比例的局部梯度均匀化的解决方案。在均匀化溶液梯度大的位置,由于在这些位置的显着构型的贡献,发现大的不确定性的T场。基于直接蒙特卡罗方法进行了数值模拟,数值蒙特卡罗结果与随机分析结果吻合良好。

英文摘要:

We present a new stochastic analysis for steady and transient one-dimensional heat conduction problem based on the homogenization approach. Thermal conductivity is assumed to be a random field K consisting of random variables of a total large number N. Both steady and transient solutions T are expressed in terms of the homogenized solution and its spatial derivatives, where homogenized solution is obtained by solving the homogenized equation with effective thermal conductivity. Both mean and variance of stochastic solutions can be obtained analytically for K field consisting of identically distributed (i.i.d) random variables. The mean and variance of T are shown to be dependent only on the mean and variance of these i.i.d variables, not the particular form of probability distribution function of i.i.d variables. Variance of temperature field T can be separated into two contributions: the ensemble contribution (through the homogenized temperature ); and the configurational contribution (through different configrations) . The configurational contribution is shown to be proportional to the local gradient of homogenized solution. Large uncertainty of T field was found at locations with large gradient of homogenized solution due to the significant configurational contributions at these locations. Numerical simulations were implemented based on a direct Monte Carlo method and good agreement is obtained between numerical Monte Carlo results and the proposed stochastic analysis.

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