Modified normalized Rortex/vortex identification method

In this paper, a modified normalized Rortex/vortex identification method named Ω̃R is presented to improve the original ΩR method and resolve the bulging phenomenon on the isosurfaces, which is caused by the original ΩR method. Mathematical explanations and the relationship between the Q criterion and Ω̃R are described in detail. In addition, the new developed formula does not require two original coordinate rotations, and the calculation of Ω̃R is greatly simplified. The numerical results demonstrate the effectiveness of the new modified normalized Rortex/vortex identification method.