Definition of vortex boundary using stagnation pressure

Secondary streamlines (left half) and stagnation pressure isolines (right half) colored by stagnation pressure, in a transverse view of the 6:1 prolate spheroid for a Reynolds number based on length of 10,000 and an angle of attack of 70 degrees. A high degree of correlation is observed between the streamlines and the stagnation pressure isolines, which are able to capture the complexity of the vortical flow. Thus, the current study proposes to use the largest closed isolines of stagnation pressure as a boundary for a vortex.