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Approach to Radiative Heat Transfer in Infrared-active Gas Including Scattering Particles through a Direct Solution Method of the Maxwell's Electro-Magnetic Equation

通过直接求解麦克斯韦电磁方程的方法研究包括散射粒子的红外活性气体中的辐射传热

基本信息

批准号：
15360110
负责人：
OKAMOTO Tatsuyuki
金额：
$ 7.55万
依托单位：
Kyoto Institute of Technology (2004-2005)Osaka University (2003)
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Scattering pattern of radiative energy scattered by particles varies with number density of particles. At the first stage of increase in number density, the intensity of scattered energy drops in the range of small scattering angle. But, the decline of scattered energy does not appear in the range of large scattering angle. In the next stage of increase in number density, the decline of scattered energy becomes remarkable in the rage of small scattering angle, and the region of fall down in scattering intensity becomes wide toward the range of large scattering angle. When the decline of scattering intensity reaches to the edge of diffraction region, the decline of scattering intensity can be recognized over the whole range of scattering angle. When the number density of scattering objects becomes much higher, scattering intensity goes down remarkably over the whole range of scattering angle. This means that the phase function based on the scattering pattern formed by a single particle … More can not be used when the number density of scattering particles are very high and the influence of multiple-scattering effect is storing. As for the number density of scattering particles, the effect of multiple scattering disappears more quickly when the distances among particles is widened in the direction of optical axis than when widened in the direction perpendicular to the optical axis. In the latter case, the critical distances among scattering angle where the multiple-scattering effect disappears is clarified.On condition that the effect of multiple scattering can be neglected, the influence of particle shape was examined by inverting the scattering pattern formed by plural scattering objects of same shape existing in arbitrary posture into particle size distribution. When the length of scattering objects is extended keeping the diameter, the mean diameter and variance of size distribution of equivalent spheres become large. But, the longer becomes the particle, variation in the mean diameter and variance becomes more moderate. When the shape of particles is rotating ellipsoid, the variance of size distribution is very small and the mean diameter obtained from the inversion of scattering pattern is equivalent to the diameter of a circle having same area as the average of projected shapes formed by the particle of arbitrary posture.Direct finite difference solution method of the electro-magnetic equation can predict the electromagnetic field among scattering particles though the Mie's scattering theory cannot predict it. On the other hand, the external product of electric field E and magnetic field H means the vector compound of energy flux in all direction. Therefore, it was not clarified how to know the radiative intensity from the electro-magnetic field obtained from the finite difference solution method. This problem was solved in this investigation. Less

粒子散射的辐射能的散射模式随粒子数密度的变化而变化。在数密度增加的第一阶段，散射能量的强度在小散射角范围内下降。但是，在大散射角范围内，散射能量并没有下降。在数密度增加的下一阶段，散射能量的下降在小散射角范围内变得显著，散射强度下降的区域向大散射角范围变宽。当散射强度的下降到达衍射区边缘时，在整个散射角范围内都可以看到散射强度的下降。当散射体的数密度很高时，散射强度在整个散射角范围内显著下降。这意味着基于单个粒子形成的散射图案的相函数 ...更多信息当散射粒子的数密度很高且多次散射效应的影响较大时，不能使用。对于散射粒子的数密度，当粒子间的距离在光轴方向上加宽时，多重散射效应消失得比在垂直于光轴的方向上加宽时更快。在后一种情况下，阐明了多重散射效应消失的散射角间临界距离，在多重散射效应可以忽略的条件下，通过将多个形状相同的散射体以任意姿态存在时形成的散射图案反演为粒径分布，考察了颗粒形状的影响。当散射体的长度保持不变时，等效球的平均直径和尺寸分布方差变大。但是，颗粒越长，平均直径和方差的变化变得越缓和。当颗粒形状为旋转椭球时，粒径分布的方差很小，由散射图反演得到的平均粒径相当于一个与任意姿态粒子投影形状的平均值具有相同面积的圆的直径。磁方程可以预测散射粒子间的电磁场，而Mie散射理论不能预测。另一方面，电场E和磁场H的外积表示所有方向上的能通量的矢量合成。因此，没有阐明如何从由有限差分解方法获得的电磁场知道辐射强度。这个问题在这次调查中得到了解决。少