Vortex Tube Reconnection at Re=104
van Rees W.M., Hussain F. and Koumoutsakos P., Vortex tube reconnection at Re=104. Physics of Fluids, 24:075105, 2012.
We present simulations of the long-time dynamics of two anti-parallel vortex tubes with and without initial axial ﬂow, at Reynolds number Re = Γ/ν = 104. Simulations were performed in a periodic domain with a remeshed vortex method using 785 × 106 particles. We quantify the vortex dynamics of the primary vortex reconnection that leads to the formation of elliptical rings with axial ﬂow and report for the ﬁrst time a subsequent collision of these rings. In the absence of initial axial ﬂow, a −5/3 slope of the energy spectrum is observed during the ﬁrst reconnection of the tubes. The resulting elliptical vortex rings experience a coiling of their vortex lines imparting an axial ﬂow inside their cores. These rings eventually collide, exhibiting a −7/3 slope of the energy spectrum. Studies of vortex reconnection with an initial axial ﬂow exhibit also the −7/3 slope during the initial collision as well as in the subsequent collision of the ensuing elliptical vortex rings. We quantify the detailed vortex dynamics of these collisions and examine the role of axial ﬂow in the breakup of vortex structures.