Analysis on Radiative Energy Transmittance Through Packed Spheres by Monte Carlo Med

用直接蒙特卡罗模拟方法研究了三维随机排列的填充球的辐射能量透过率。球体直径远大于辐射能的波长。得到以下结果.规则排列的微球的辐射透过率比随机排列的微球的辐射透过率低，且这种效应随着微球的堆积密度的增大而显著.为了研究填充球的侧壁对透射率的影响，进行了实验研究，并与直接蒙特卡罗模拟结果进行了比较。结果表明，由于靠近侧壁的薄层的堆积密度较低，通过该薄层的局部透过率低于通过该薄层的其它部分的透过率。并且，总透射率特性被认为是透射率较低的床的中心区域的特性和透射率较高的外围区域的特性的总和.为了取代严格但耗时的直接蒙特卡罗模拟方法，通过修正连续模型的消光系数和散射相函数，建立了一个简单的模型来分析辐射能量通过填充球的透射率。新模型的计算结果与直接蒙特卡罗方法的计算结果吻合较好。

Radiative energy transmittance is studied through three-dimensional packed spheres with random arrangement by using a direct Monte Carlo simulation method. The sphere diameter is far greater than the wave length of the radiative energy. The following results are obtained.1. The radiative transmittance through regularly-packed spheres is lower than the one through randomly-packed spheres, and this effect becomes eminent when the packing density of the spheres becomes higher.2. To study the effect of side walls of the packed spheres on the transmittance, an experiment is carried out and the result is compared with the one obtained by using the direct Monte Carlo simulation. The result shows that the local transmittance through the thin layer of the bed adjacent to the side walls is lower than the one through other part of the bed due to the lower packing density at the layer. And, the total transmittance characteristics are considered to be the sum of the characteristics of the central area of the bed whose transmittance is lower and the characteristics of the peripheral area whose transmittance is higher.3. To substitute the rigorous but time-consuming direct Monte Carlo simulation method, a simple model is developed to analyze the transmittance of radiative energy through packed spheres by correcting the extinction coefficient and the scattering phase function of the continuous model. The result of the newly developed model agrees well with the result of the direct Monte Carlo method.