Compact manifold representation of airfoil wake-vortex gust interaction*

Airfoil wake dynamics can be described by a collection of dynamically important modes. 

This translates to the existence of a low-dimensional representation of the underlying dynamics. 

This study considers the complex dynamics of vortex gust-airfoil wake interaction around a NACA0012 airfoil over a range of angles of attack. 

While undisturbed flows in the present example can be easily characterized in a low-dimensional space through linear techniques, it is very challenging to obtain a compact representation of the wakes under the influence of strong vortex gusts.

To extract a universal manifold for a variety of complex wakes, we develop a physics-guided nonlinear autoencoder. 

The current technique provides a physically-interpretable low-dimensional manifold that covers a variety of wake arrangements, which is difficult for conventional autoencoder-based techniques.

Furthermore, the present latent manifold can be leveraged to assess how complex wakes are affected and modified by disturbances in a low-dimensional space.

This approach achieves significant compression of unsteady aerodynamic flows and identifies the relevant latent space coordinates to optimally describe the seemingly complex dynamics with an extremely small number of variables.