  We study numerically the induction mechanisms generated from an array of
helical motions distributed along a cylinder. Our flow is a very idealized
geometry of the columnar structure that has been proposed for the convective
motion inside the Earth core. Using an analytically prescribed flow, we apply a
recently introduced iterative numerical scheme to solve the induction equation
and analyze the flow response to externally applied fields with simple
geometries (azimuthal, radial, etc.). Symmetry properties allow us to build
selected induction modes whose interactions lead to dynamo mechanisms. Using an
induction operator formalism, we show how dipole and quadrupole dynamos can be
envisioned from such motions.
