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The influence of an axial through-flow on the spatiotemporal growth behaviorof different vortex structures in the Taylor-Couette system with radius ratioeta=0.5 is determined. The Navier Stokes equations (NSE) linearized around thebasic Couette-Poiseuille flow are solved numerically with a shooting method ina wide range of through-flow strengths Re and different rates of co- andcounterrotating cylinders for toroidally closed vortices with azimuthal wavenumber m=0 and for spiral vortex flow with m=+1 and m=-1. For each of thesethree different vortex varieties we have investigated (i) axially extendedvortex structures, (ii) axially localized vortex pulses, and (iii) vortexfronts. The complex dispersion relations of the linearized NSE for vortex modeswith the three different m are evaluated for real axial wave numbers for (i)and over the plane of complex axial wave numbers for (ii,iii). We have alsodetermined the Ginzburg-Landau amplitude equation (GLE) approximation in orderto analyze its predictions for the vortex stuctures (ii,iii). Criticalbifurcation thresholds for extended vortex structures are evaluated. Theboundaries between absolute and convective instability of the basic state forvortex pulses are determined with a saddle-point analysis of the dispersionrelations. Finally, the linearly selected front behavior of growing vortexstructures is investigated. For the two front intensity profiles (increasing inpositive or negative axial direction) we have determined front velocities,axial growth rates, and the wave numbers and frequencies of the unfoldingvortex patterns with azimuthal wave numbers m=0, +1, -1, respectively.Comment: 15 pages, 9 figure

Spiral and Taylor vortex fronts and pulses in axial through flow