  Diverging supersonic flows are accelerating, as in the case of a de Laval
nozzle, and the same concept has been applied for acceleration of
magnetohydrodynamic flows in the universe. Here, we study the dynamics of
"non-diverging" cylindrical supersonic flows and show that they can be
accelerated by effects of radiative cooling and the tangled magnetic field. In
addition to radiative cooling of the jet materials (cooling effect), conversion
of the ordered magnetic field into the turbulent one (conversion effect) and
dissipation of the turbulent magnetic field (dissipation effect) are formulated
according to our study on pulsar wind nebulae. Although each of the cooling and
conversion effects is an ineffective acceleration process, the terminal
velocity of magnetized cylindrical jets attains about half of the maximum
possible value when the cooling, conversion and dissipation effects work
simultaneously. The radiation efficiency is also about half of the total
luminosity of the jet in the case of maximal acceleration. The concept for flow
acceleration by the non-ideal MHD effects may be useful for studying
relativistic jets in active galactic nuclei, in which the region near the jet
axis is expected to be cylindrical and kink unstable.
