Identified vortices in the Orszag-Tang test flow at t = 1.0. Top panel: position and the size of the identified vortices. Green colored vortices rotate counter-clockwise, while the pink ones rotate clockwise. Bottom panels: close-ups on four different regions of the flow with identified vortices. The velocity field is represented by instantaneous streamlines. Thesizeofeachvortexis computedaccording to Eq. (24).