Numerical Simulation of Flapping Foil Experiment Based on Compressible Hydrodynamic Equations

The large-eddy simulation numerical approach based on the compressible hydrodynamic equations was used to simulate turbulent flow around a system of two flappers and a stationary foil. Detailed analysis of this flow was carried out with the simulated data. Results have been compared with the available experimental data. The mean flow profiles were found to be predicted well, and the simulated turbulent intensity was in agreement with the measured data in the area where large eddies dominate. Extensive studies were conducted of the unsteady outer flow's effect, produced by the two upstream flappers, on the boundary layer of the stationary foil. The unsteadiness in the outer flow was found to be small; consequently, the response of the boundary layer of the stationary foil occurred mainly in the first harmonic of the flapper's oscillation. An interesting phenomenon of tangential velocity phase shift in the stationary foil's boundary layer was observed. This result qualitatively agrees with the experimental measurement as well.