A Surrogate-Based \(e^N\) Transition Prediction Method for Three-Dimensional Compressible Boundary Layers

Local stability theory (LST) combined with an \(e^N\) method is a well-suited approach for predicting transition. However, simpler or surrogate LST models are often used in an automated transition prediction framework for robustness and efficiency reasons. There are, however, few surrogate-based stability methods for the instabilities encountered in three-dimensional compressible flows. To address this problem, this paper proposes a radial-basis-function-based surrogate model capable of reproducing the instability characteristics of two-dimensional Tollmien-Schlichting waves and stationary cross-flow instabilities. The basic flows necessary to set up the model stem from compressible local Falkner-Skan-Cook similarity solutions. The suitability of the proposed method is demonstrated by N-factor computations for three ATTAS flight test points at transonic conditions.