# Vortex core line

In scientific visualization, a vortex core line is a line-like feature tracing the center of a vortex within a velocity field.

## Detection methods

Several methods exist to detect vortex core lines in a flow field. Jiang, Machiraju & Thompson (2004) studied and compared nine methods for vortex detection, including five methods for the identification of vortex core lines. Although this list is incomplete, they considered it representative for the state of the art (as of 2004).

One of these five methods is by Sujudi & Haimes (1995): in a velocity field v(x,t) a vector x lies on a vortex core line if v(x,t) is an eigenvector of the tensor derivative $\nabla \boldsymbol{v}(\boldsymbol{x},t)$ and the other – not corresponding – eigenvalues are complex.