The Research and Simulation (Modelling) of the Destruction of a Single Abrasive Particle during Waterjet Cutting

The article presents the results of experimental studies of differences in the nature of impact destruction of single garnet grains penetrating the target material, and presents the results of numerical simulation (modeling) of the contact interaction of an abrasive particle with a flat obstacle, which allowed determining the volume ablation of the material under the action of a single abrasive particle, and makes it possible to predict the performance of waterjet cutting.

ЧИСЛЕННОЕ МОДЕЛИРОВАНИЕ ВЗАИМОДЕЙСТВИЯ НЕДОРАСШИРЕННОЙ СВЕРХЗВУКОВОЙ СТРУИ ГАЗА С ПЛОСКОЙ ПРЕГРАДОЙ

The results of numerical modeling based on the nonstationary Reynolds-averaged Navier – Stokes equations for the interaction of an underexpanded supersonic gas jet with a flat obstacle, which was established at different distances from the nozzle exit section are presented. The results of the calculations are presented in the form of the distribution of the Mach number and the density gradient in the calculated region, and the pressure and friction coefficients over the surface of the plate. The results of the numerical calculation are compared with the experimental data.

Humans exploit the biomechanics of bipedal gait during visually guided walking over complex terrain

How do humans achieve such remarkable energetic efficiency when walking over complex terrain such as a rocky trail? Recent research in biomechanics suggests that the efficiency of human walking over flat, obstacle-free terrain derives from the ability to exploit the physical dynamics of our bodies. In this study, we investigated whether this principle also applies to visually guided walking over complex terrain. We found that when humans can see the immediate foreground as little as two step lengths ahead, they are able to choose footholds that allow them to exploit their biomechanical structure as efficiently as they can with unlimited visual information. We conclude that when humans walk over complex terrain, they use visual information from two step lengths ahead to choose footholds that allow them to approximate the energetic efficiency of walking in flat, obstacle-free environments.