  There exists a large body of previous work using reduced two-dimensional
models of the SOL, which model fluctuations in the drift-plane but approximate
parallel transport with effective loss terms. Full size three-dimensional
simulations of SOL turbulence in experimental geometries are now possible, but
are far more computationally expensive than 2D models. We therefore use a
flux-tube geometry model of the scrape-off layer to compare the results of 2D
simulations to 3D simulations with a similar setup, looking for systematic
differences. Overall there is good agreement in the basic radial profiles,
probability distribution functions, and power spectra of fluctuations. However,
the average temperature is over-predicted in 2D relative to 3D, and we explain
the difference in terms of the effect of geometrical simplifications of devices
at low power. Varying geometric parameters, we find that supersonic flow in the
divertor leg, which occurs because our simulations do not include neutrals and
so represent low-recycling conditions, means that the divertor leg length only
has a weak effect on the output. Finally, we examine the effect of altering the
magnitude of source and sink terms in 2D, concluding that they cannot easily be
used to recreate both the density and temperature profiles observed in 3D
simultaneously.
