Three-dimensional numerical simulations of a four-wing flapping micro aerial vehicle (FMAV) with actual experimentally captured wing membrane kinematics have been performed using an immersed boundary method Navier-Stokes finite volume solver. To successfully simulate the clap and fling motion involving the wing intersection, the numerical solver has been specifically modified to use a newly improved interpolation template searching algorithm to prevent divergence. Reasonable agreement was found between the numerical and experimental results, with the first and second force peaks from the experimental results well captured by the simulations, which was not possible in the past. Moreover, a "V-shaped linked" vortex was observed, which was similar to the vortical structures found in other experiments and simulations. A wing drag analysis showed that the drag magnitude of the clap and fling configuration was about 2.5 times that of the single-wing configuration. Visualizations of the flowfields through pressure contours and vortical isosurfaces led to a better understanding of the underlying flapping-wing aerodynamics. The ability to accurately simulate the FMAV with flexible wings opened up many opportunities for further FMAV design-related problems. ... Read more

3D Numerical simulations of a biplane flapping wing MAV have been performed using an immersed boundary method Navier-Stokes finite volume solver. To obtain a realistic simulation, the wing deformation has been captured using a stereo-vision system. The raw data obtained is further post-processed using Kriging interpolation and the results with and without the interpolation are compared. Results show that Kriging interpolation gives smoother force variation and is able to give reasonable converged solution using only ten wing positions (frames) over one period. The simulation results managed to capture the first peak of the experimental force results both in terms of approximate location and magnitude. However, the simulation only managed to capture the second peak in term of location; its magnitude is smaller than the experimental force. Various reasons for the discrepancies have been discussed. Nevertheless, the simulations reveal strong leading edge and tip vortices, which will enable us to get a better understanding of the underlying flapping wing aerodynamics. ... Read more

Uncertainty Quantication (UQ) for CFD-based ship design can require a large number of simulations, resulting in signicant overall computational cost. Presently, we use an existing method, multi-delity Kriging, to reduce the number of simulations required for the UQ analysis of the performance of a sailing yacht hull, considering uncertainties in the tank blockage, mass and centre of gravity. We compare the UQ results with experimental values. ... Read more