Modelling cavitation erosion using fluid–material interaction simulations

Abstract

Material deformation and pitting from cavitation bubble collapse is investigated using fluid and material dynamics and their interaction. In the fluid, a novel hybrid approach, which links a boundary element method and a compressible finite difference method, is used to capture non-spherical bubble dynamics and resulting liquid pressures efficiently and accurately. The bubble dynamics is intimately coupled with a finite-element structure model to enable fluid/structure interaction simulations. Bubble collapse loads the material with high impulsive pressures, which result from shock waves and bubble re-entrant jet direct impact on the material surface. The shock wave loading can be from the re-entrant jet impact on the opposite side of the bubble, the fast primary collapse of the bubble, and/or the collapse of the remaining bubble ring. This produces high stress waves, which propagate inside the material, cause deformation, and eventually failure. A permanent deformation or pit is formed when the local equivalent stresses exceed the material yield stress. The pressure loading depends on bubble dynamics parameters such as the size of the bubble at its maximum volume, the bubble standoff distance from the material wall and the pressure driving the bubble collapse. The effects of standoff and material type on the pressure loading and resulting pit formation are highlighted and the effects of bubble interaction on pressure loading and material deformation are preliminarily discussed.

Numerical Investigation of the Dynamics of Pressure Loading on a Solid Boundary from a Collapsing Cavitation Bubble

“…and 3920 respectively. The first observed pressure peak is due to liquid jet impact and second peak due to the collapse of the bubble ring or torus, similar to the observations made in Chahine et al [7]. The corresponding pressure and density contours for the observed pressure peaks are shown next in figure 4 and figure 5.…”

High-speed video microscopy and numerical modeling of bubble dynamics near a surface of urinary stone

“…At P 01 , this maximum was due to constructive interference of pressure waves converging toward the axis from the toroidal collapse of the bubble ring, as previously described. 36 The maximum pressure spikes had durations $1 ns and quickly decayed off-axis. Longer ($30 ns) pulses covered larger areas and, regardless of the amount of gas in the bubble, had substantial pressure amplitudes [ Fig.…”

“…Second, the stone was modeled as a rigid surface, whereas the finite acoustic impedance and elasticity of urinary stones have been shown to affect the predicted pressure amplitudes. 24,[33][34][35][36] Third, the pressure during focusing events becomes nearly singular and, to remain finite, depends on actual dissipative mechanisms. The influence of viscosity on pressure generated by the collapsing bubbles was not investigated in this report.…”

Local energy of a bubble system and its loss due to acoustic radiation

“…The weakly compressible potential flow is modelled here using a recently developed implementation of the boundary integral method (BIM) for a bubble in a compressible liquid (Wang & Blake 2010, Wang 2013, 2014. By the way, nonspherical bubble dynamics in a compressible liquid have been simulated using domain approaches coupled with various interface-capturing schemes (Johnsen & Colonius 2006, Turangan et al 2008, Terashima et al 2009, Fuster et al 2011, Hiao et al 2014, Chahine et al 2015, 2016.…”