Resonating Reflex A Critical Investigation Of The Physical An... by John Rudd

Self-resonating cavitation waterjet (SRCW) has rapidly developed and been widely used in cleaning fields due to its non-thermal and environmentally friendly machining. The flow field structure of the waterjet can be directly perceived through simulation, which can provide theoretical support for realizing the modulation of the erosion characteristics, optimizing nozzle structure. When the pressure at the low-pressure zone is lower than the vapor pressure, the cavitation occurs. The obtained results show that the sudden change of the flow velocity at the outlet of the nozzle leads to the forms of the low-pressure zone. For better understanding the physical phenomena, the velocity, the pressure distributions, and the cavitation characteristics were investigated. Results of numerical simulations and experimental data frequency bands obtained by the Fast Fourier transform (FFT) method were in very good agreement. Collected data from experimental tests were used to validate the model. The numerical model employs the mixture two-phase model, coupling the realizable turbulence model and Schnerr–Sauer cavitation model. A three-dimensional computational fluid dynamics (CFD) model was developed to analyze the unsteady characteristics of the self-resonating jet. Copyright © 2013 John Wiley & Sons, Ltd.The cavitation phenomenon of the self-resonating waterjet for the modulation of erosion characteristics is investigated in this paper. A higher order model is also proposed, and its advantages and drawbacks are discussed. Through these tests, some other numerical specificities of the SPH method are discussed, such as the self-redistribution of the particles occurring during the Lagrangian evolution. The convergence of our model is heuristically proved on these nonlinear prototype tests, showing at the same time the very satisfactory level of accuracy reached. On the shown test problems, it is also evidenced that some numerical tools are crucial to ensure the robustness and accuracy of the standard SPH method. The role of numerical errors in the development of acoustic frequencies in the pressure signals is discussed, as well as the influence of the choice of the sound velocity. In particular, a great care is paid to the dynamic part of the solution, which is critical to the local hydrodynamic load prediction. The present work aims at investigating various numerical aspects of this method, often little mentioned in literature. These rather critical prototype problems shall constitute suitable test cases to get through when building a free-surface SPH model. In this paper, an in-depth study of SPH method, in its original weakly compressible version, is achieved on dedicated 2D and 3D free-surface flow test cases.

Resonating Reflex A Critical Investigation Of The Physical An... by John Rudd