  We study the effect of nonlocal optical response on the optical properties of
metallic nanowires, by numerically implementing the hydrodynamical Drude model
for arbitrary nanowire geometries. We first demonstrate the accuracy of our
frequency-domain finite-element implementation by benchmarking it in a wide
frequency range against analytical results for the extinction cross section of
a cylindrical plasmonic nanowire. Our main results concern more complex
geometries, namely cylindrical and bow-tie nanowire dimers that can strongly
enhance optical fields. For both types of dimers we find that nonlocal response
can strongly affect both the field enhancement in between the dimers and their
respective extinction cross sections. In particular, we give examples of
maximal field enhancements near hybridized plasmonic dimer resonances that are
still large but nearly two times smaller than in the usual local-response
description. At the same time, for a fixed frequency the field enhancement and
cross section can also be significantly more enhanced in the nonlocal-response
model.
