Numerical modeling of laser generated cavitation bubbles with the finite volume and volume of fluid method, using OpenFOAM

Koch, Max; Lechner, Christiane; Reuter, Fabian; Köhler, Karsten; Mettin, Robert; Lauterborn, Werner

doi:10.1016/j.compfluid.2015.11.008

Cited by 210 publications

(145 citation statements)

References 61 publications

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“…Short time scales and small spatial scales as well as nontransparent parts of the flows partly impede further investigation. Therefore, additional insights are also expected from advanced numerical simulations [34][42] [50][51] [52][53] [54].…”

Section: Resultsmentioning

confidence: 99%

Mechanisms of single bubble cleaning

Reuter

Mettin

2016

Ultrasonics Sonochemistry

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124

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The dynamics of collapsing bubbles close to a flat solid is investigated with respect to its potential for removal of surface attached particles. Individual bubbles are created by nanosecond Nd:YAG laser pulses focused into water close to glass plates contaminated with melamine resin micro-particles. The bubble dynamics is analysed by means of synchronous high-speed recordings. Due to the close solid boundary, the bubble collapses with the well-known liquid jet phenomenon. Subsequent microscopic inspection of the substrates reveals circular areas clean of particles after a single bubble generation and collapse event. The detailed bubble dynamics, as well as the cleaned area size, is characterised by the non-dimensional bubble stand-off γ=d/Rmax, with d: laser focus distance to the solid boundary, and Rmax: maximum bubble radius before collapse. We observe a maximum of clean area at γ≈0.7, a roughly linear decay of the cleaned circle radius for increasing γ, and no cleaning for γ>3.5. As the main mechanism for particle removal, rapid flows at the boundary are identified. Three different cleaning regimes are discussed in relation to γ: (I) For large stand-off, 1.8<γ<3.5, bubble collapse induced vortex flows touch down onto the substrate and remove particles without significant contact of the gas phase. (II) For small distances, γ<1.1, the bubble is in direct contact with the solid. Fast liquid flows at the substrate are driven by the jet impact with its subsequent radial spreading, and by the liquid following the motion of the collapsing and rebounding bubble wall. Both flows remove particles. Their relative timing, which depends sensitively on the exact γ, appears to determine the extension of the area with forces large enough to cause particle detachment. (III) At intermediate stand-off, 1.1<γ<1.8, only the second bubble collapse touches the substrate, but acts with cleaning mechanisms similar to an effective small γ collapse: particles are removed by the jet flow and the flow induced by the bubble wall oscillation. Furthermore, the observations reveal that the extent of direct bubble gas phase contact to the solid is partially smaller than the cleaned area, and it is concluded that three-phase contact line motion is not a major cause of particle removal. Finally, we find a relation of cleaning area vs. stand-off γ that deviates from literature data on surface erosion. This indicates that different effects are responsible for particle removal and for substrate damage. It is suggested that a trade-off of cleaning potential and damage risk for sensible surfaces might be achieved by optimising γ.

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Section: Resultsmentioning

confidence: 99%

Mechanisms of single bubble cleaning

Reuter

Mettin

2016

Ultrasonics Sonochemistry

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124

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“…Except few exceptions [76] these methods have not been widely developed yet in the context of cavitation. Instead algebraic VOF are becoming popular for the simulation of cavitating bubbles [145,122,121,214]. These methods are very similar to DIM and require to manipulate the fundamental transport equation for the color function to introduce terms that limit the diffusion of the interface.…”

Section: Methodsmentioning

confidence: 99%

A Review of Models for Bubble Clusters in Cavitating Flows

Fuster

2018

Flow Turbulence Combust

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This paper reviews the various modeling strategies adopted in the literature to capture the response of bubble clusters to pressure changes. The first part is focused on the strategies adopted to model and simulate the response of individual bubbles to external pressure variations discussing the relevance of the various mechanisms triggered by the appearance and later collapse of bubbles. In the second part we review available models proposed for large scale bubbly flows used in different contexts including hydrodynamic cavitation, sound propagation, ultrasonic devices and shockwave induced cavitation processes. Finally we discuss the main challenges of cavitation models.

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“…Compressibility is included on the right hand side, which contains the compressibility of both phases (liquid and gas) with ψ = Dρ/Dp from the Equation of State (EOS). For the gas phase a polytropic EOS is used while for the liquid phase the Tait EOS (Macdonald 1969) is applied, similar to the cavitation bubble simulations in Koukouvinis et al (2016a,b) and Koch et al (2016).…”

Section: Methodsmentioning

confidence: 99%

“…For simplicity we model the initial (laser created) cavitation bubble consisting of non-condensable gas starting from a small volume at high pressure. The sharp interface of the cavitation bubble is captured by solving the transport equation for the volume fraction of the liquid (Miller et al 2013;Koch et al 2016):…”

Section: Methodsmentioning

confidence: 99%

Wall shear stress from jetting cavitation bubbles

et al. 2018

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The collapse of a cavitation bubble near a rigid boundary induces a high-speed transient jet accelerating liquid onto the boundary. The shear flow produced by this event has many applications, examples are surface cleaning, cell membrane poration, and enhanced cooling. Yet the magnitude and spatio-temporal distribution of the wall shear stress are not well understood, neither experimentally nor by simulations. Here we solve the flow in the boundary layer using an axisymmetric compressible Volume of Fluid (VOF) solver from the OpenFOAM framework and discuss the resulting wall shear stress generated for a non-dimensional distance, γ = 1.0 (γ = h/R max , where h is the distance of the initial bubble centre to the boundary, R max the maximum spherical equivalent radius of the bubble). The calculation of the wall shear stress is found reliable once the flow region with constant shear rate in the boundary layer is determined. Very high wall shear stresses of 100 kPa are found during the early spreading of the jet followed by complex flows composed of annular stagnation rings and secondary vortices. Although the simulated bubble dynamics agrees very well with experiments we obtain only qualitative agreement with experiments due to inherent experimental challenges.

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Numerical modeling of laser generated cavitation bubbles with the finite volume and volume of fluid method, using OpenFOAM

Cited by 210 publications

References 61 publications

Mechanisms of single bubble cleaning

Mechanisms of single bubble cleaning

A Review of Models for Bubble Clusters in Cavitating Flows

Wall shear stress from jetting cavitation bubbles

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