An embedded boundary approach for the simulation of a flexible flapping wing at different density ratio

We have developed a strong-coupling approach based on a uniformly-applied Eulerian description for both fluid and solid and provided a simple monolithic formulation to compute highly flexible structures interacting with surrounding fluid flows. Using a fast-tracking method and a fast solver for the modified pressure equation with variable density, we keep the same low computational cost as in the uniform density case studied previously. The new algorithm is first validated by the simulation of the self-sustained oscillation of a flexible plate. Then, it is applied to study the effect from density ratio on a flexible plate flapping with incoming flow. The simulation shows strong effect of density ratio on the pattern of fluid–structure interaction and the propulsion performance through the change in mass ratio and frequency ratio.