When applying any vortex identification method, e.g. Q-criterion, to the turbulent flow field, we can only obtain a field of vortices consisting of thousands of vortices. The usual way to extract individual vortices out from the vortex field is to adjust the threshold of vortex identification criterion and expect vortices can detangle from the complex field. However, the performance is not very good in most cases.

Most of the vortices are still connected and couldn’t be separated from each other at a quite high threshold. Meanwhile, weaker vortices start to disappear with an increasing threshold.

With VATIP, we are able to extract the axis-lines of vortices from the complex flow field. The following figure shows the axis lines obtained from our DNS data by VATIP.

We can also classify vortices into different categories accourding to the topological features of individual vortices!

Finally, check out the beautiful vortices extracted by VATIP.