  Giant Molecular Clouds (GMCs) are observed to be turbulent, but theory shows
that without a driving mechanism turbulence should quickly decay. The question
arises by which mechanisms turbulence is driven or sustained. It has been shown
that photoionising feedback from massive stars has an impact on the surrounding
GMC and can for example create vast HII bubbles. We therefore address the
question of whether turbulence is a consequence of this effect of feedback on
the cloud. To investigate this, we analyse the velocity field of simulations of
high mass star forming regions by studying velocity structure functions and
power spectra. We find that clouds whose morphology is strongly affected by
photoionising feedback also show evidence of driving of turbulence by
preserving or recovering a Kolmogorov-type velocity field. On the contrary,
control run simulations without photoionising feedback have a velocity
distribution that bears the signature of gravitational collapse and of the
dissipation of energy, where the initial Kolmogorov-type structure function is
erased.
