Introduction

Coherent structures and vortices sometimes are misunderstood for not having a clear definition. In general ways, any form of pattern arising in the flow that has an effect on it is considered a coherent structure. Meanwhile, the vortices are commonly explained as the existence of some kind of rotation in the flow. The difficulty on identifying these vortices it’s in the fact that is not so clear to measure the extension of the vortex from its center of rotation. All of this becomes more complicated when we have the interaction between multiples coherent structures. According to Shawn et al (2005) [SHAWN2005] the definition is:

“It is generally accepted that flows with general time dependence admit emergent patterns which influence the transport of tracers, those structures are often generically refered to as Coherent Structures”

In short we can say that vortices are one of the specific definition for coherent structures.

[SHAWN2005]

Shawn C. Shadden, Francois Lekien, Jerrold E. Marsden (2005) Definition and properties of Lagrangian coherent structures from finite-time Lyapunov exponents in two-dimensional aperiodic flows Physica D 212 (2005) 271-304