Archimedes screws have gained popularity recently as an eco-friendly, low-cost, and reliable hydropower option. Due to their complex geometry, it has been very difficult to measure and visualize the fluid properties within a screw during operation. Throughout this thesis two computational fluid dynamic models were developed and validated to help fill this void in the literature. The first modelled a single screw bucket, allowing for data to be collected from a geometrically perfect screw, with no blade-trough gap. The second model was geometrically identical but had a domain of four buckets to include and investigate the effects of gap leakage between the blades and the screw’s trough. The effect of the gap was investigated with respect to the torque and rotational speed, kinetic energy within a bucket, pressure along the screw’s trough, the fill height in a bucket, and the wall shear stress along the screw’s blades.