Simulation of simplified-frigate airwakes using a lattice-Boltzmann method

The airwakes of two simplified-frigate shapes were analysed as part of a study of the complex flow field generated as a helicopter interacts with the airwake of a ship. The current computational studies simulate ship airwake without an immersed helicopter rotor. This flow simplification provides insight into the environment a maritime helicopter pilot will encounter when operating from a frigate or frigate-like ship. The flow around the simplified frigate shapes were simulated using the lattice-Boltzmann flow solver PowerFLOW and the results compared to experimental data. That data included the surface flow visualization on one shape and unsteady off-body velocity measurements on the other. From both the surface and off-body mean flow comparisons, it is shown that the lattice-Boltzmann method captures the correct flow topology. The root-mean-square (RMS) of the fluctuating velocities of the simulated airwake are also seen to match well with the measured RMS velocities. The presented results indicate that the lattice-Boltzmann algorithm will capture both the mean and unsteady portion of the airwake on and off the surface of the frigate for low to moderate wind angles. Crown Copyright (C) 2007 Published by Elsevier Ltd. All rights reserved.