Pairing of vortex rings

Pairing is an interaction between vortex rings which are rotating and translating in the same sense. The parameters for this simulation were taken from Verzicco, Iafrati, Riccardi and Fatica, 1997, `Analysis of the sound generated by the pairing of two axisymmetric co-rotating vortex rings', Journal of Sound and Vibration, 200(3): 347--358. The images correspond to figure 3 of that paper. The results are not identical in part because the model used here is inviscid.

The images show azimuthal vorticity with highest values in red and lowest in blue. The rings move from right to left.

Nondimensional time: 0.

Nondimensional time: 2.

Nondimensional time: 4.

Nondimensional time: 6.

Nondimensional time: 8.

Nondimensional time: 10.