@article{oai:nitech.repo.nii.ac.jp:00005250,
 author = {Allen, J. J. and Naitoh, Takashi},
 issue = {6},
 journal = {PHYSICS OF FLUIDS},
 month = {May},
 note = {A method for producing a vortex ring with an apparatus that utilizes a time varying aperture that closes during ring production is shown to have the capability for the production of rings of low nondimensional energy similar to a Hill’s spherical vortex. This represents a difference of more than 50%, in terms of the nondimensional energy, of those which have been produced with fixed diameter generators. Experiments show that modulation of the rate at which the vortex ring generator produces kinetic energy, circulation, and impulse is the critical factor in determining what type of ring is formed., application/pdf},
 pages = {061701-1--061701-4},
 title = {Experimental study of the production of vortex rings using a variable diameter orifice},
 volume = {17},
 year = {2005}
}