The Rayleigh prolongation factor at small bubble to wall stand-off distances

Abstract

The Rayleigh collapse time is the time it would take to shrink an empty spherical bubble in an infinite liquid domain to zero size, which is a function of ambient pressure and initial bubble radius. If a solid boundary is located in the vicinity of the shrinking or collapsing bubble, then liquid flow is hindered, such that the collapse time is prolonged. This can be quantified with the Rayleigh prolongation factor $k$ . Here, we provide $k$ for intermediate to smallest bubble to wall stand-off distances. It is measured with single laser-induced cavitation bubbles in water close to a solid boundary. Maximum bubble radii are determined from microscopic high-speed imaging at one million frames per second. Collapse times are measured acoustically via the acoustic transients emitted during bubble seeding and collapse. The experimental findings are compared, with good agreement, to numerical simulations based on a volume of fluid method. As a result, a polynomial fit of $k$ versus stand-off distance is given for the near-wall bubble collapse in water. Then the influence of the viscosity on $k$ is studied numerically in the near-wall regime.

In situ measurement of cavitation damage from single bubble collapse using high-speed chronoamperometry

“…Please take note that for the three measurements the instance of collapse differs because the bubble lifetime, i.e. the time from generation to collapse, is proportional to and also a function that is sensitively dependent on in this near-wall regime [44] , [45] . A further difference concerns the value of the plasma generation peak which is largest again for , i.e.…”

Cavitation erosion by shockwave self-focusing of a single bubble

“…Role of the Needle Jet in Cavitation Erosion. As the stand-off goes to zero, the bubble dynamics becomes approximately that of a hemispherical bubble, which in potential flow approximation can be considered equivalent a spherical bubble due to symmetry considerations [68] . Consequently, for a maximum energy concentration is expected.…”

“…1 a). is measured in direction perpendicular to the solid as discussed in [68] . To conduct a stand-off dependent study, a pristine surface areas of the sample is positioned close to the spot of bubble generation and a number N of identical bubbles are generated.…”

“…a solid or fluid boundary. Recently, the dynamics of a bubble at closest distance to a solid boundary have gained attention in experimental studies [98] , [99] , [67] , [68] . Cavitation bubbles at interfaces in general develop non-spherical dynamics and can produce fast and microscopic flows.…”

Experimental Study on the Underwater Explosion Bubble Near deformable boundary

“…In recent years, scholars have increasingly focused on research related to the near-field underwater explosion [8]. Zhang, Liu, Wang, Tang and Ma [9] and Reuter, Zeng and Ohl [10] studied the near-field bubble pulsation characteristics near the rigid wall through experimental and numerical methods. However, in practical applications, the near-field underwater explosion can cause significant deformation of the structure.…”