Simulations of the shock waves and cavitation bubbles during a three-dimensional high-speed droplet impingement based on a two-fluid model

Niu, Yang-Yao; Wang, Hongwei

doi:10.1016/j.compfluid.2016.05.018

Cited by 14 publications

(15 citation statements)

References 33 publications

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“…The second test case examined is a planar 'drop' impact on a solid wall for which experimental data are available [12]. The main mechanisms noticed both in the experimental work [10,12] and past numerical simulations [102,104,105] are jetting, as well as shock and expansion waves; these are also identified in the present study. In the aforementioned compressible numerical studies, cavitation was not modelled and different impact conditions were simulated compared to the present work.…”

Section: Planar Drop Impactmentioning

confidence: 55%

“…More recently, Niu and Wang [105] developed a compressible two-fluid model for the Euler equations and they proposed an approximated linearized Riemann solver for the liquid-gas interface. Surface tension was neglected due to high We number, as well as in the above high-speed droplet impacts.…”

Section: Droplet Impact and Compressibility Effectsmentioning

confidence: 99%

“…With the exception of the observations of Field et al [12], to the author's best knowledge, there is no other experiment and no numerical study published in which the formation and development and cavitation within the bulk of the impacting droplet is considered; the only relevant numerical study is the work of Niu et al [105], where cavitation zones have been identified but without actually simulating the phase-change process. The aforementioned experimental data of the Riemann problem for the multi-material Euler equations is discussed; this methodology was used to obtain the exact solution for the benchmark Riemann problem.…”

Section: The Present Contributionmentioning

confidence: 99%

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Modelling cavitation during drop impact on solid surfaces

Kyriazis

Koukouvinis

Gavaises

2018

Advances in Colloid and Interface Science

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The impact of liquid droplets on solid surfaces at conditions inducing cavitation inside their volume has rarely been addressed in the literature. A review is conducted on relevant studies, aiming to highlight the differences from non-cavitating impact cases. Focus is placed on the numerical models suitable for the simulation of droplet impact at such conditions. Further insight is given from the development of a purpose-built compressible two-phase flow solver that incorporates a phase-change model suitable for cavitation formation and collapse; thermodynamic closure is based on a barotropic Equation of State (EoS) representing the density and speed of sound of the co-existing liquid, gas and vapour phases as well as liquid-vapour mixture. To overcome the known problem of spurious oscillations occurring at the phase boundaries due to the rapid change in the acoustic impedance, a new hybrid numerical flux discretization scheme is proposed, based on approximate Riemann solvers; this is found to offer numerical stability and has allowed for simulations of cavitation formation during drop impact to be presented for the first time. Following a thorough justification of the validity of the model assumptions adopted for the cases of interest, numerical simulations are firstly compared against the Riemann problem, for which the exact solution has been derived for two materials with the same velocity and pressure fields. The model is validated against the single experimental data set available in the literature for a 2-D planar drop impact case. The results are found in good agreement against these data that depict the evolution of both the shock wave generated upon impact and the rarefaction waves, which are also captured reasonably well. Moreover, the location of cavitation formation inside the drop and the areas of possible erosion sites that may develop on the solid surface, are also well captured by the model. Following model validation, numerical experiments have examined the effect of impact conditions on the process, utilizing both planar and 2-D axisymmetric simulations. It is found that the absence of air between the drop and the wall at the initial configuration can generate cavitation regimes closer to the wall surface, which significantly increase the pressures induced on the solid wall surface, even for much lower impact velocities. A summary highlighting the open questions still remaining on the subject is given at the end.

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Section: Planar Drop Impactmentioning

confidence: 55%

Section: Droplet Impact and Compressibility Effectsmentioning

confidence: 99%

Section: The Present Contributionmentioning

confidence: 99%

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Modelling cavitation during drop impact on solid surfaces

Kyriazis

Koukouvinis

Gavaises

2018

Advances in Colloid and Interface Science

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“…On the modelling side, droplet impact on solid surfaces has been investigated 60 numerically by many researchers using various numerical algorithms to account for the different phases, such as marker-and-cell (MAC) finite differences [33], front tracking approach [12], Volume of Fluid [34], multicomponent Euler solver [35] or two-fluid model for Euler equations [36], to name a few. Sanada et al [35] investigated the impact of a liquid droplet on solid surface, the shock-wave structures, interfaces and jetting as well as solid surface compliance.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the investigation of [13] has focused on the shock confinement inside isolated liquid volumes and proposed a new model for erosion based on cavitation caused by trapped shocks. However, cavitation is not modelled in the aforementioned works, although the work of 75 [36] identifies the potential vapour regions. Cavitation induction during droplet impact on wall is studied by [37], where numerical results are compared to experimental findings from literature and found in good agreement.…”

Section: Introductionmentioning

confidence: 99%

Cavitation induction by projectile impacting on a water jet

Stavropoulos-Vasilakis

Kyriazis

Koukouvinis

et al. 2019

International Journal of Multiphase Flow

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This is the accepted version of the paper.This version of the publication may differ from the final published version.Permanent repository link: https://openaccess.city.ac.uk/id/eprint/21817/ Link to published version: http://dx. AbstractThe present paper focuses on the simulation of the high-velocity impact of a projectile impacting on a water-jet, causing the onset, development and collapse of cavitation. The simulation of the fluid motion is carried out using an explicit, compressible, density-based solver developed by the authors using the OpenFOAM library. It employs a barotropic two-phase flow model that simulates the phase-change due to cavitation and considers the co-existence of noncondensable and immiscible air. The projectile is considered to be rigid while its motion through the computational domain is modelled through a direct-forcing Immersed Boundary Method. Model validation is performed against the experiments of Field et al. [1], who visualised cavity formation and shock propagation in liquid impacts at high velocities. Simulations unveil the shock structures and capture the high-speed jetting forming at the impact location, in addition to the subsequent cavitation induction and vapour formation due to refraction waves. Moreover, model predictions provide quantitative information and a better insight on the flow physics that has not been identified from the reported experimental data, such as shock-wave propagation, vapour formation quantity and induced pressures. Furthermore, evidence of the Richtmyer-Meshkov instability developing on the liquid-air interface are predicted when sufficient dense grid resolution is utilised. 45 cavitation erosion development.Along the same lines, the theoretical study of [31], has analytically examined the liquid drop impacts on solid surfaces, while the experiments reported in [1] for liquid droplets impacting on a solid surface, reveal the strong effects of com-the nozzle, in: 10th International Cavitation Symposium, 2018.

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