Methods for density control are of critical importance for future long pulse tokamaks. The EMC3-EIRENE code is being used to investigate the applicability of 3D non-axisymmetric fields for density control in standard and advanced divertor configurations in spherical tokamaks. Part of this effort is understanding Scrape Off layer (SOL) transport mechanisms once axisymmetry is broken. Unique experimental measurements of SOL flow structures at the Mega Ampere Spherical Tokamak (MAST) present an ideal laboratory for comparison between experiment and modeling. A Coherence Imaging Spectroscopy (CIS) diagnostic was deployed for the MAST 2013 scientific campaign, during which flow measurements were taken of high field side fueling experiments that show the appearance of field-aligned flows around the center column. EMC3-EIRENE simulations are in good agreement with these measurements, and in tandem with 1D analysis show that the code captures the fundamental dynamics underlying the observed behavior. Neutral fueling of a flux tube creates a local plasma source, this drives a local increase in static plasma pressure, which in turn leads to a flow away from the particle source in that flux tube. Cross field diffusion then damps these parallel flows.