Numerical simulations of an acoustophoresis-assisted fluid jet polishing process

The current work presents the numerical simulations of a novel acoustophoresis-assisted Fluid Jet Polishing (FJP) process. The underlying principle of the new technique involves migrating abrasive particles to desired locations (pressure nodes) within the jet using standing acoustic waves. The migration of particles occurs on account of the radiation force arising from the difference in the acoustic impedance of the particles and the carrier fluid. In the present work, we analyze the proposed FJP procedure using multiphase simulations involving a combination of Eulerian and Lagrangian approaches. The influence of acoustophoresis on circular and square cross-sectioned nozzles has been primarily evaluated. Though the pressure nodes in circular nozzles can help achieve precise annular erosion, they do not alter the inhomogeneous W-shaped erosion profile usually observed in conventional FJP systems. In contrast, the acoustic forcing in square cross-section nozzles propels the particles towards the jet axis, thereby manifesting a U-shaped erosion profile for specific operating conditions that have been identified via a systematic analysis. Such particle focussing/redistribution capabilities provide a unique means of controlling erosion, removing machining inhomogeneity, enhancing the material removal rate, and pattern formation during the FJP process.