Symbolic regression modelling of the linear growth rates of stationary cross-flow instabilities

Abstract Accurately predicting the growth rates of stationary cross-flow instabilities is crucial for understanding transition mechanisms in swept-wing configurations, which can significantly impact aerodynamic performance. This paper introduces a model for the prediction of cross-flow instability growth rates, focusing on both accuracy and ease of implementation. The proposed model consists of straightforward expressions involving key boundary layer quantities. Validation against established methods demonstrates that the new model achieves comparable or superior accuracy in predicting growth rates. Additionally, tests conducted on a three-dimensional (3-D) prolate spheroid show strong alignment with transition lines computed by means of exact linear stability. Overall, this model provides a practical and efficient alternative for accurately predicting cross-flow transitions in complex 3-D geometries, contributing to improved aerodynamic design and analysis.