  The decay of kinetic helicity is studied in numerical models of forced
turbulence using either an externally imposed forcing function as an
inhomogeneous term in the equations or, alternatively, a term linear in the
velocity giving rise to a linear instability. The externally imposed forcing
function injects energy at the largest scales, giving rise to a turbulent
inertial range with nearly constant energy flux while for linearly forced
turbulence the spectral energy is maximum near the dissipation wavenumber.
Kinetic helicity is injected once a statistically steady state is reached, but
it is found to decay on a turbulent time scale regardless of the nature of the
forcing and the value of the Reynolds number.

Solar and Stellar Astrophysics;Chaotic Dynamics;Atmospheric and Oceanic Physics;Fluid Dynamics;Space Physics