Two-point correlation to identify vortex cores

Hello everyone,

I am trying to imitate the follwing:

Source: Wang, J. S., Feng, L. H., Wang, J. J., & Li, T. (2018). Görtler vortices in low-Reynolds-number flow over multi-element airfoil. Journal of Fluid Mechanics, 835, 898-935.

Which is to findthe two-point correlation functions between swirling strength and velocity for estimation of the conditionally averaged velocity field given a vortex core.

I have multiple files that contains velocity and location at different time steps, I can also use image processing as well if nessecary.

Any idea if there is a matlab package out there that could help do such thing?

Appreciate your help and thank you!