Low-velocity impact damage in multiscale hierarchical composites comprising glass fiber weaves reinforcing a vinyl ester matrix with tailored location of multiwall carbon nanotubes is assessed through the changes of electrical resistance before and after impact. The location of the multiwall carbon nanotubes within the multiscale composite is controlled from manufacturing, rendering two hierarchical architectures. In the first one, as-received glass fiber weaves are used and the multiwall carbon nanotubes are only dispersed within the matrix, while in the second one the multiwall carbon nanotubes are dispersed within the matrix and also bonded to the glass fibers. Spatial electrical resistance maps are able to track the damage progression and growth of damage extension under consecutive impacts and the results are correlated to stresses determined by finite element analysis and ultrasonic C-scanning. The correlation between the electrical mapping and finite element analysis showed that the panels containing multiwall carbon nanotubes on the fiber are more sensitive to delamination and interfacial damage than the ones containing multiwall carbon nanotubes only dispersed within the polymer matrix.

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The hydrodynamic behavior of a turbulent flow and the mixing characteristics generated by a V-grooved axial impeller inside an agitated tank reactor were investigated both experimentally and numerically. Angle resolved Particle Image Velocimetry (PIV) techniques with an angular displacement Δθ=5° have been applied and two aerodynamic planes along the blades were considered. PIV-based results were compared to those obtained by Large Eddy Simulation (LES), used with the dynamic Smagorinsky-Lilly sub-grid scale (SGS) model. Results showed the existence of distinctive recirculation zones in the aerodynamic planes, and new additional frequencies in the impeller stream, induced by the grooves. A decrease of mixing time of about 11 % was obtained experimentally, consequence of the better suction induced by the grooved blades in the early stages of mixing. Mean velocities, vorticity, TKE obtained from LES showed a good agreement with the PIV-based results. The distributions of turbulence dissipation rate ε were similar to those obtained from PIV, however showing high under-predicted magnitudes.