Multifidelity CFD analysis for ducted hydrokinetic turbine design

Hydrokinetic turbines generate power from marine and riverine currents. These turbines can be modeled using computational fluid dynamics (CFD) tools. CFD is particularly useful for analyzing ducted hydrokinetic turbines because it captures the complex flow interactions between the duct and the rotor. This work demonstrates a multifidelity CFD framework for analyzing and optimizing ducted hydrokinetic turbines, balancing computational cost with accuracy at different design stages. The framework is first validated against experimental results for a freestream hydrokinetic turbine before being applied to ducted configurations. Three fidelity levels are proposed: (1) low-fidelity body-force approaches for efficient initial duct design optimization, (2) medium-fidelity blade element momentum theory coupled with CFD to capture two-way duct-rotor interactions, and (3) high-fidelity rotating sliding mesh simulations for final design validation. The results demonstrate that body-force methods can efficiently model the ducted system while maintaining sufficient accuracy for design optimization. Blade element momentum theory coupled to CFD provides improved accuracy for detailed design refinement. The high-fidelity CFD is too computationally expensive for design iterations but serves as a crucial validation tool.