Effects of Meshing, Solver Parameters and Post-processing on Aero-optical Image Quality Metric Modeling

摘要

Environmental effects on the Image Quality (IQ) of the Thirty Meter Telescope (TMT) are estimated using Computational Fluid Dynamics (CFD) simulations. These simulations estimate, among others, refractive index fluctuations as well as wind jitter and blur. As the design matures, guidance obtained from these numerical experiments can influence significant cost-performance trade-offs and even component survivability. The stochastic nature of environmental conditions results in the generation of a large computational solution matrix in order to statistically predict Observatory Performance. Moreover, the relative contribution of selected key subcomponents to IQ increases the parameter space and thus computational cost, while dictating a reduced prediction error bar. The current study presents the strategy followed to minimize prediction time and computational resources, the subsequent physical and numerical limitations and finally the approach to mitigate the issues experienced. In particular, the paper describes the meshing methodology, a mesh-independence study and the effect of various numerical parameters and errors on the TMT IQ metric.