非球形粒子及其弥散系的矢量辐射传输特性研究

The particle systems involved in natural or industrial processes are often presented in two forms, the sparse dispersion system and the dense dispersion system. Early studies usually assume that particles are spheroids, but this will lead to a greater error to the study of radiation transmission. The research on the vector radiation transmission of non-spherical particles and their dispersion systems is a common basic problem to be solved. The project mainly researches on the following three aspects: the modeling and scattering characteristics of non-spherical particles, the sparse and dense particle system modeling and radiative transfer characteristics, and the efficient solution to the vector radiation transfer equation. Aiming at the key scientific issues involved, this project intends to develop a modeling method of non-spherical particles based on the spherical superposition model, the solving method of the vector radiation transfer equation by the backward and forward Monte Carlo method and the modeling method of the dense dispersion particle system based on the multiphase radiative transfer equation. In addition, a fast parallel algorithm based on GPU is developed. This project will also carry out verification experiments using the excellent sand environment simulation system, verify the particle model and the solving method, and optimize the vector radiation transfer model of particle system. Through the in-depth study of the vector radiation transfer characteristics of dust particles and their dispersion system, we can grasp the radiative transfer rule of dust particles, which is expected to provide a theoretical basis for the related applications.

自然界或工业过程中所涉及的粒子系常以稀疏弥散系和稠密弥散系两种形式呈现。早期的研究通常假设粒子为球体，但这会给辐射传输研究带来较大的误差。对于非球形粒子及其弥散系的矢量辐射传输研究是亟待解决的共性基础问题。本项目主要研究内容包括三个方面：非球形粒子的建模和散射特性、稀疏及稠密粒子系的建模和辐射传输特性、矢量辐射传输的高效求解方法。针对其中所涉及的关键科学问题，本项目拟发展基于球叠加模型的非球形粒子建模方法、反正向蒙特卡洛法的矢量辐射传输方程求解方法和基于多相辐射传输方程的稠密弥散粒子系的建模方法研究上述问题。此外，发展基于GPU的快速并行算法。本项目还将利用性能优良的沙尘环境模拟系统开展验证实验，验证粒子模型及求解方法，优化粒子系矢量辐射传输模型。通过对沙尘粒子及其弥散系矢量辐射传输特性的深入研究，掌握粒子系辐射传输规律，有望为相关应用提供理论依据。

自然界或工业过程中所涉及的粒子系常以稀疏弥散系和稠密弥散系两种形式呈现。早期的研究通常假设粒子为球体，但这会给辐射传输研究带来较大的误差。对于非球形粒子及其弥散系的矢量辐射传输研究是亟待解决的共性基础问题。在项目的支持下，课题组完成的研究内容包括三个主要方面：(1)通过对模拟月壤形态的分析，提出了基于球叠加模型的建模方法，针对各种粒子模型发展了统一的建模方法，并发展了针对大粒子的蒙特卡洛光线跟踪法与针对小粒子的离散偶极子近似法，研究了各种不同类型粒子、粒子系的辐射特性。(2)提出了三种光线跟踪法，发展了多维梯度折射率介质矢量辐射传输的方法，该问题是辐射传输领域的难点问题之一。(3)完善了辐射传输求解的格子玻尔兹曼方法。格子玻尔兹曼方法具有灵活简便、并行效率高等优点，近10多年来受到学者们的关注，发展了一些格子玻尔兹曼模型，但缺乏严格的数学基础，导致应用受限。项目组通过严格的数学推导，构建了该方法的严格的理论基础。项目组在课题的支持下，发表了大量高水平的学术论文，其中一些是行业内的顶级期刊。