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International audience; It is notoriously difficult for artists to control liquids while generating plausible animations. We introduce a new liquid control tool that allows users to load, transform, and apply precomputed liquid simulation templates in a scene in order to control a particle-based simulation. Each template instance generates control forces that drive the global simulated liquid to locally reproduce the templated liquid behavior. Our system is augmented with a variable proportion of temporary particles to help efficiently reproduce the templated liquid density, with fewer requirements on the surrounding environment. The resulting control strategy adds only a small computational overhead, leading to quick visual feedback for resolutions allowing interactive simulation. We demonstrate the robustness and ease of use of our method on various examples in 2D and 3D.

This article presents an analysis of the effectiveness of available numerical techniques in mapping the characteristic behavior of ballistic ceramics under projectile impact conditions. As part of the work, the ballistic tests were performed on the layered ceramic/steel composite armor and tested with the 7.62 × 39 mm, armor-piercing incendiary (API) BZ projectile. The experimental tests were then mapped using computer simulations. In numerical analyses, four different techniques were used to describe cubic ceramic tiles Al2O3 placed on the ARMOX 500T steel backing plate, i.e.,: the Finite Element Method without Erosion (FEM), Finite Element with erosion (FEM + Erosion), Smoothed Particles Hydrodynamics (SPH) and a hybrid method that converts finite elements to SPH particles after exceeding the defined failure criteria (FEM to SPH conversion). The effectiveness of the individual methods was compared in terms of quality (mapping of characteristic phenomena occurring during the penetration process), quantity (bulge height of the backing plate) and time needed to complete the calculations. On the basis of the results of the experiments and numerical simulations, it was noticed that the most accurate reproduction of the phenomenon of ballistic impact of AP projectiles on ceramic/steel composite armor can be obtained by using a hybrid method, incorporating the conversion of finite elements into SPH particles. This method should be used in cases where accuracy of the results is more important than the time required to complete the calculations. In other situations where the purpose of the calculation is not to determine, for example, the exact value of penetration depth but only to observe a certain trend, the FEM method with defined erosion criteria (variant 2), which is more than 10 times faster, can be successfully used.

International audience; When a material is submitted to a dynamic compression, a shock wave propagates through the bulk and potentially interacts with a free surface. If this surface has geometrical defects such as grooves, some material ejection can occur. The energy of the high velocity ejecta is an area of concern for many applications, such as industrial safety, pyrotechnics or inertial confinement fusion. We have studied this phenomenon of microjetting from calibrated grooves in laser shock-loaded Cu samples, combining complementary experimental, numerical and analytical approaches, in order to investigate the formation and the fragmentation of the jets over ranges of small spatial (~µm) and temporal (~ns) scales and extremely high strain rates (~107 s−1). Various grooves were used with different depths and aperture half-angles (20°, 30°, 45°). The velocities measured by fast shadowgraphy and heterodyne velocimetry were compared to numerical predictions using the finite element or the smoothed particles hydrodynamics formulations with the Radioss code. Size distribution of the ejecta was inferred from rough measurements of the debris sizes and compared to analytical predictions from a probability law. © 2016, Society for Experimental Mechanics, Inc.