[1] P Coussot, Yield stress fluid flows: A review of experimental data, J. Non Newton. Fluid 211, 31 (2014).

[2] D De Kee, R P Chhabra, A photographic study of shapes of bubbles and coalescence in non Newtonian polymer solutions, Rheol. Acta 27, 656 (1988).

[3] N Dubash, I A Frigaard, Propagation and stopping of air bubbles in Carbopol solutions, J. Non Newton. Fluid 142, 123 (2007).

[4] T Podgorski, A Belmonte, Surface folds during the penetration of a viscoelastic fluid by a sphere, J. Fluid Mech. 460, 337 (2002).

[5] T Podgorski, A Belmonte, Surface folding of viscoelastic fluids: Finite elasticity membrane model, Eur. J. Appl. Math. 15, 385 (2004).

[6] H Lhuissier, B Neel, L Limat, Viscoelasticity breaks the symmetry of impacting jets, Phys. Rev. Lett. 113, 194502 (2014).

[7] C Palacios Morales, R Zenit, The formation of vortex rings in shear thinning liquids, J. Non Newton. Fluid 194, 1 (2013).

[8] Supplementary material can be found at https://doi.org/10.4279/PIP.080007

[9] R H Hernandez, B Cibert, C Bechet, Experiments with vortex rings in air, Europhys. Lett. 75, 743 (2006).

[10] I S Sullivan, J J Niemela, R E Hershberger, D Bolster, R J Donnell, Dynamics of thin vortex rings, J. Fluid Mech. 609, 319 (2008).

[11] S Perrard, Y Couder, E Fort, L Limat, Leidenfrost levitated liquid tori, Europhys. Lett. 100, 54006 (2012).

[12] T Bohr, C Ellegaard, A Espe Hansen, A Haaning, Hydraulic jumps, flow separation and wave breaking: An experimental study, Physica B 228, 1 (1996).

[13] A Andersen, T Bohr, T Schnipper, Separation vortices and pattern formation, Theor. Comp. Fluid Dyn. 24, 329 (2010).

[14] T R N Jansson, M P Haspang, J H Jensen, P Hersen, T Bohr, Polygons on a Rotating Fluid Surface, Phys. Rev. Lett. 96, 174502 (2006).

[15] H A Abderrahmane, K Siddiqui, G H Vatistas, Rotating waves within a hollow vortex core, Exp. Fluids 50, 677 (2011).

[16] K Shariff, A Leonard, Vortex Rings, Annu. Rev. Fluid Mech. 24, 235 (1992).