基于动态粒子参数选择的水雾透过率计算

Numerical calculation of transmittance of fogs based on dynamic particle parameter selection

为了研究多次散射效应对辐射在雾中传输特性的影响,提出了一种多粒子雾层模型,该模型中雾滴粒子为半径不同的球形水滴粒子。雾滴粒子半径被分为多个区间,计算了不同半径区间内雾滴粒子的传输近似光学参数。提出了一种基于动态粒子参数选择的蒙特卡罗法,并模拟0.85μm和4μm辐射在重度平流雾、中度平流雾、重度辐射雾和中度辐射雾中的传输。分析了传输距离对透过率和计算时间的影响,并与传统的蒙特卡罗法的计算结果进行比较。结果表明:相比于4μm辐射,0.85μm辐射在雾中的透射能力更强;基于动态粒子参数选择的蒙特卡罗法与传统蒙特卡罗法计算得到的透过率随传输距离的变化曲线具有相同的趋势,传输距离为150 m时,两种方法对0.85 μm和4 μm辐射在重度平流雾中的透过率的绝对误差分别为0.0483和0.0015;传输距离为400 m时,相较于传统的蒙特卡罗法,基于动态粒子参数选择的蒙特卡罗法对4 μm辐射在重度平流雾中的传输计算效率可提升44%。基于动态粒子参数选择的蒙特卡罗法计算雾中的远距离辐射传输,可有效缩短计算时间。该研究结果对雾天的目标识别与探测有重要意义。

To investigate the influence of multiple scattering effects on the transmission characteristics of radiation through fog,a polydisperse fog layer consisting of spherical water particles of different radii was proposed in this study. The radii of fog particles were first divided into several radius regions,and the transport approximation optical parameters of fog particles in each radius region were calculated. A Monte Carlo method based on dynamic particle parameter selection was next proposed,and the propagation of0. 85-and 4-μm radiations through heavy advection fog,moderate advection fog,heavy radiation fog,and moderate radiation fog was simulated. The influence of the propagation distance on the transmittance and computational time was analyzed,and the results were compared with those of the ordinary Monte Carlo method. The results show that when compared with 4-μm radiation,0. 85-μm radiation has better transmission properties in fog. The trends of transmittance versus propagation distance obtained using the Monte Carlo method based on dynamic particle parameter selection and the ordinary Monte Carlo method are similar. When the propagation distance is 150 m,the absolute errors of the two methods for transmittance of 0. 85-and 4-μm radiations through heavy advection fog are 0. 048 3 and 0. 001 5,respectively. Compared with that of the ordinary Monte Carlo method,the computational efficiency of the Monte Carlo method based on dynamic particle parameter selection for 4-μm radiation through heavy advection fog is as high as 44%. The Monte Carlo method based on dynamic particle parameter selection should be used for radiation transfer calculation in fog for long propagation distance cases,which can effectively shorten the computational time. The results of this study are significant for target recognition and detection in foggy weather.