Comparison of Navier-Stokes and Lattice-Boltzmann Method CFD Approaches for Ship-Rotor Interactional Aerodynamics Using Cartesian GPU Solvers

During rotorcraft ship-deck landing operations, interactions of the highly unsteady ship airwake with the rotor wake create a highly complex flow field. CFD is a strong candidate for ship-rotor interactional analysis. Yet, traditional Delayed Detached Eddy Simulations can take days or weeks to simulate these problems on CPU-based HPC clusters. Hence, the present work considers mid-fidelity GPU-accelerated approaches for ship airwake and ship-rotor interactional aerodynamics simulations. The Orchard Navier-Stokes GPU solver, available in the CREATE™-AV Helios suite, as well as a newly developed Lattice-Boltzmann Method (LBM) plugin for Orchard, LBMCart, were evaluated on the same computational grid for standalone ship airwake and ship-rotor interactional simulations. Results showed that LBMCart maintained equal or better accuracy than Orchard while running over 17x faster for the standalone ship airwake case. In the ship-rotor interactional case, Orchard showed a more complex rotor wake vortex structure as compared to LBMCart, but both solvers showed similar rotor aerodynamic loads and load frequencies. The present study shows the strong potential of the LBM for Helios simulations. With the increasing appeal of massively parallelized GPU computing, a GPU-based LBM solver may be a worthwhile candidate for inclusion in future Helios releases.