  We investigate the scattering phenomena produced by a general finite-range
nonseparable potential in a multi-channel two-probe cylindrical nanowire
heterostructure. The multi-channel current scattering matrix is efficiently
computed using the R-matrix formalism extended for cylindrical coordinates.
Considering the contribution of the evanescent channels to the scattering
matrix, we are able to put in evidence the specific dips in the tunneling
coefficient in the case of an attractive potential. The cylindrical symmetry
cancels the "selection rules" known for Cartesian coordinates. If the
attractive potential is superposed over a non-uniform potential along the
nanowire, then resonant transmission peaks appear. We can characterize them
quantitatively through the poles of the current scattering matrix. Detailed
maps of the localization probability density sustain the physical
interpretation of the resonances (dips and peaks). Our formalism is applied to
a variety of model systems like a quantum dot, a core/shell quantum ring or a
double-barrier, embedded into the nanocylinder.
