“…Vortex research in Cartesian coordinates includes the Green-Taylor vortex (Taylor and Green, 1937) and the helicoid vortex discussed herein El-Genk, 2008a, 2010b andd). Various researchers selected spherical coordinates (Gol'Dshtik and Yavorskii, 1986;Hwang and Chwang, 1992;Tsukker, 1955), but the vast majority of the research found in the literature is in cylindrical coordinates (Aboelkassem, Vatistas, and Esmail, 2005;Batchelor, 1964;Burgers, 1948;Chepura, 1969;Gortler, 1954;Lamb, 1932;Loitsyanskiy, 1953;Martynenko, 1989;Newman, 1959;Rankine, 1858;El-Genk, 2008a, 2010b andd;Sullivan, 1959;Squire, 1965). Cylindrical coordinates are chosen primarily due to its geometric simplicity and excellent mapping of the vortex behavior onto a coordinate system-in particular, as a 3D vortex spins azimuthally, stretching about the z axis, the vortex velocity field engulfs a cylindrical geometry.…”