热晕效应数值模拟中对计算参数的选取

Choosing computing parameters in the numerical simulation of thermal blooming effects

根据数值计算的抽样原则,对激光大气传输数值模拟中如何准确地选取计算参数作了比较全面 的分析,导出计算参数选取所应遵循的判据。结合高斯光束及平台光束准直传输热畸变后的相位分布,得到了 网格间距与Bradley Hermann热畸变参数的关系。在算出此热畸变参数后,便可选定合适的网格间距,由数值 结果便能准确评价实际激光大气传输的效果。数值结果表明,相同网格数、不同网格间距下数值结果的差别相 对较大,若网格间距选取不当,将给数值结果带来较大误差。

In the numerical simulation of thermal blooming effects, how to choose the grid spacing and other computing parameters correctly is introduced. Based on the sample principles of numerical calculation, the choice of computing parameters is analyzed. Combining the blooming distortion phase distribution for a Gaussian beam and a uniform irradiance circular beam, the relation between the grid spacing and Bradley-Hermann distortion number is deduce. The correct grid spacing could be chosen from the value of the thermal distortion number. In addition, we can correctly evaluate the effects of laser propagation in the real atmosphere from the numerical results. The results show that the difference of the numerical results with same grid numbers and different grid spacing is relatively big. Moreover, the error of numeral results is big, if the chose of grid spacing is unsuitable.