Splitting and jetting of cavitation bubbles in thin gaps

Zeng, Qingyun; Gonzalez-Avila, Silvestre Roberto; Ohl, Claus‐Dieter

doi:10.1017/jfm.2020.356

Cited by 56 publications

(37 citation statements)

References 43 publications

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“…The compressibilities Dρ/Dp are determined by the equation of state for the gas and liquid phases, which for simplicity we choose to be the ideal gas and fluid laws, neglecting higher-order effects of temperature and pressure (Miller et al 2013;Koch et al 2016). Numerical simulations using compressibleInterFOAM have recently been performed to study cavitation and jetting in thin gaps (Zeng et al 2020).…”

Section: Experimental and Numerical Methodsmentioning

confidence: 99%

Experimental and numerical study of laser-induced secondary jetting

et al. 2022

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The generation of liquid jets and drops using tightly focused femtosecond laser pulses near a liquid–air interface is a convenient contactless solution for printing functional materials as well as bio-materials. Jets and drops emerge following the nucleation of a cavitation bubble in the liquid bulk by a laser-induced plasma. During the initial expansion of the bubble, a thin and fast jet is produced at the liquid surface. Moments later a second thick and slow jet emanates from the surface when the bubble has nearly deflated. Despite potential applications, little is known about the mechanism behind this complex phenomenology. Here, experiments and simulations are used to investigate this two-jet process. Counter-intuitively, the second jet is not the result of bubble expansion, as with the first jet, but originates from the secondary flows induced by the bubble dynamics. Our study links the second jet properties to the control parameters of the problem and establishes a phase diagram for its emergence.

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Section: Experimental and Numerical Methodsmentioning

confidence: 99%

Experimental and numerical study of laser-induced secondary jetting

et al. 2022

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“…The problem consists of two phases (gas and liquid), where both are compressible and immiscible Newtonian fluids. As heat and mass transfer between two phases are negligible (Koukouvinis et al 2018;Zeng et al 2020), the governing equations for the flow are the equations of continuity and momentum:…”

Section: Methodsmentioning

confidence: 99%

Wall shear stress from jetting cavitation bubbles: influence of the stand-off distance and liquid viscosity

Zeng

Ohl

2021

J. Fluid Mech.

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We study systematically the cavitation-induced wall shear stress on rigid boundaries as a function of liquid viscosity $\mu$ and stand-off distance $\gamma$ using axisymmetric volume of fluid (VoF) simulations. Here, $\gamma =d/R_{max}$ is defined with the initial distance of bubble centre from the wall $d$ and the bubble equivalent radius at its maximum expansion $R_{max}$ . The simulations predict accurately the overall bubble dynamics and the time-dependent liquid film thickness between the bubble and the wall prior to the collapse. The spatial and temporal wall shear stress is discussed in detail as a function of $\gamma$ and the inverse Reynolds number $1/Re$ . The amplitude of the wall shear stress is investigated over a large parameter space of viscosity and stand-off distance. The inward stress is caused by the shrinking bubble and its maximum value $\tau _{mn}$ follows $\tau _{mn} Re^{0.35}=-70\gamma +110$ (kPa) for $0.5<\gamma <1.4$ . The expanding bubble and jet spreading on the boundary produce an outward-directed stress. The maximum outward stress is generated shortly after impact of the jet during the early spreading. We find two scaling laws for the maximum outward stress $\tau _{mp}$ with $\tau _{mp} \sim \mu ^{0.2} h_{jet}^{-0.3} U_{jet}^{1.5}$ for $0.5\leq \gamma \leq 1.1$ and $\tau _{mp} \sim \mu ^{-0.25} h_{jet}^{-1.5} U_{jet}^{1.5}$ for $\gamma \geq 1.1$ , where $U_{jet}$ is the jet impact velocity and $h_{jet}$ is the distance between lower bubble interface and wall prior to impact.

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“…This high resolution is required to sufficiently resolve the bubble at its minimum volume. Existing studies on the influence of confinement on bubble dynamics assume an undriven, initially small, bubble at high pressure to match laser-induced or spark-generated cavitation bubbles in experiments [8][9][10]20]. The initial conditions in this study are the static equilibrium conditions.…”

Section: Simulation Setupmentioning

confidence: 99%

“…Bubble oscillations in narrow gaps have received attention only recently [8][9][10], but none of these studies considered acoustic cavitation dynamics confined by rigid boundaries. To the authors' best knowledge, this study is the first to address this knowledge-gap.…”

Section: Introductionmentioning

confidence: 99%