论文标题
向上过度旋转的压缩对流。 iii。一维雷诺应力模型的校准参数
Upward Overshooting in Turbulent Compressible Convection. III. Calibrate Parameters for One-dimensional Reynolds Stress Model
论文作者
论文摘要
在本文中,我们用一维雷诺应力模型的系数校准了从湍流可压缩对流中向上过度冲动的三维数值模拟产生的数据。已经发现,校准的对流和各向同性系数几乎与纯对流区校准的系数相同。但是,校准的扩散系数与纯对流区域校准的系数有显着差异。我们怀疑边界引起的扩散效应比相邻稳定区更强。我们已经检查了降级近似的有效性。我们发现,降级近似在三阶矩上的预测不令人满意。但是,对其衍生物的预测要好得多。它解释了为什么Reynolds应力模型的性能合理地应用于真实的恒星。使用校准的系数,我们已经在雷诺应力模型上解决了整个非局部湍流方程。我们发现,雷诺应力模型成功地产生了热调节层和湍流耗散层,这些层已在三维数值模拟中鉴定出来。我们建议使用温度扰动和péclet数的自动相关的拐点作为分别测量热调节层和湍流耗散层的范围的指标。该结果可能会提供有关雷诺应激模型在一维恒星结构和进化模型中应用的实用指导。
In this paper, we calibrate the coefficients for the one-dimensional Reynolds stress model with the data generated from the three-dimensional numerical simulations of upward overshooting in turbulent compressible convection. It has been found that the calibrated convective and isotropic coefficients are almost the same as those calibrated in the pure convection zone. However, the calibrated diffusive coefficients differ significantly from those calibrated in the pure convection zone. We suspect that the diffusive effect induced by the boundary is stronger than by the adjacent stable zone. We have checked the validity of the downgradient approximation. We find that the prediction of the downgradient approximation on the third-order moments is unsatisfactory. However, the prediction on their derivatives is much better. It explains why the performance of the Reynolds stress model is reasonable in application to the real stars. With the calibrated coefficients, we have solved the full set of nonlocal turbulent equations on Reynolds stress model. We find that the Reynolds stress model has successfully produced the thermal adjustment layer and turbulent dissipation layer, which were identified in the three-dimensional numerical simulations. We suggest to use the inflection point of the auto-correlation of temperature perturbation and the Péclet number as the indicators on measuring the extents of the thermal adjustment layer and turbulent dissipation layer, respectively. This result may offer a practical guidance on the application of the Reynolds stress model in 1D stellar structure and evolution models.