Image

Figure1: Streamlines and pathlines in a model of a rotating vortex rope. (a) The vortex core line based on streamlines (according to Sujudi and Haimes) is shown as a thick grey tube (it is the only grey line which also is a helix). (b) The vortex core line based on pathlines (shown in yellow on the right) has the same pitch but a larger radius (it is the only helical pathline, shown in thick magenta).
Figure1 : Streamlines and pathlines in a model of a rotating vortex rope. (a) The vortex core line based on streamlines (according to Sujudi and Haimes) is shown as a thick grey tube (it is the only grey line which also is a helix). (b) The vortex core line based on pathlines (shown in yellow on the right) has the same pitch but a larger radius (it is the only helical pathline, shown in thick magenta).

Publication

This image has been taken from the following publication:
2008
Raphael Fuchs, Ronald Peikert, Helwig HauserORCID iD, Filip Sadlo, Philipp Muigg
Parallel Vectors Criteria for Unsteady Flow Vortices
TVCG, 14(3):615-626, May 2008. [Paper] 		Journal Paper (without talk)