Abstract: An ground-up investigation of the unsteady hydrodynamics influencing tidal turbine performance in a representative unsteady offshore environment. This entails the usage of three-dimensional Computational Fluid Dynamic (CFD) simulations to model the interactions between tidal rotors (represented by the actuator line method for efficiency) and unsteady flow (generated through the Divergence-Free Synthetic Eddy Method) for a range of flow scenarios and channel configurations. The research objectives are to (a) improve unsteady interactions between the actuator line method and turbulent flows, and (b) explore how those turbulent flows affect rotor performance and wake recovery.