Numerical investigation of bubble dynamics using tabulated data

Kyriazis, Nicholas; Koukouvinis, Phoevos; Gavaises, Manolis

doi:10.1016/j.ijmultiphaseflow.2017.04.004

Cited by 45 publications

(31 citation statements)

References 39 publications

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“…The numerical method has been described in detail and validated in [8], here only the main features are discussed. The 2-D Euler equations in r-z cylindrical coordinates with a geometric source term accounting for cylindrical symmetry are explicitly solved [9]:…”

Section: Methodsmentioning

confidence: 99%

“…In this section the results of a parametric bubble collapse are presented. The collapse of a vapour bubble in the vicinity of a wall is investigated for a different set of configurations (see Table 1 and [8] for details concerning the configuration). In Table 1 the ratio dw/Rb,0 is the distance from the wall to the center of the bubble divided by the initial bubble radius, pinf is the pressure of the liquid, T is the initial temperature for both the liquid and the vapour and τ is the Rayleigh collapse time for each case.…”

Section: Cav18-05102mentioning

confidence: 99%

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Heating Effects During Bubble Collapse Using Tabulated Data

Kyriazis¹,

Koukouvinis²,

Gavaises³

et al. 2018

Proceedings of the 10th International Symposium on Cavitation (CAV2018)

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An explicit density-based solver for the compressible Navier-Stokes equations able to simulate cavitating flows has been developed and utilised for the simulation of collapsing vapour bubbles. Phase-change is considered by employing the homogeneous equilibrium model (HEM). The wide variation of Mach numbers between the liquid, vapour and mixture regimes is tackled by a Mach consistent numerical flux, suitable for subsonic up to supersonic flow conditions. Time discretisation is performed using a second order low storage Runge-Kutta scheme. Thermodynamic closure is achieved by utilising the Helmholtz energy equation of state (EoS), making feasible simulation of conditions at subcritical and supercritical regions considering the variations of liquid and vapour temperatures during bubble collapse. In order to reduce the computational cost associated with the solution of the Helmholtz EoS at each time step, a tabulated data technique has been followed. The unstructured thermodynamic table, containing the thermodynamic properties derived from the Helmholtz EoS, has been constructed for n-dodecane, which has been the considered as the working fluid. The efficiency of the method is enhanced by a static linked-list algorithm for searching among the elements of the table. In addition, a finite element bilinear interpolation is used for approximating the unknown thermodynamic properties. After validating the numerical method, parametric studies considering 2-D axisymmetric vaporous bubble collapse in the proximity of a wall have been performed at conditions realised in micro-orifice flow passages. The temperature and pressure changes on the wall are estimated as function of the surrounding liquid pressure, the initial bubble radius and the location of the wall from the center of the initial bubble, revealing the expected range of variation as function on the set parameters.

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Section: Methodsmentioning

confidence: 99%

Section: Cav18-05102mentioning

confidence: 99%

Heating Effects During Bubble Collapse Using Tabulated Data

Kyriazis¹,

Koukouvinis²,

Gavaises³

et al. 2018

Proceedings of the 10th International Symposium on Cavitation (CAV2018)

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“…In the literature, however, it is commonly assumed that liquids behave according to the stiffened gas EoS and the gas/vapour as an ideal gas [58,93,94] despite the strong evidence that the stiffened gas EoS may not be adequate, since it cannot replicate at the same time both the correct density and the speed of sound of the liquid [95]. For this reason, many researchers have recently turned towards more accurate relationships for describing the materials involved [57] and [96] developed by the authors. Such accurate EoS have been formulated by NASA [97,98] or in other investigations [99].…”

Section: Thermodynamic Closurementioning

confidence: 99%

“…-Based on this assumed u , solve each material separately, with a single material Riemann solver, assuming that the contact discontinuity is a moving wall at velocity u wall = u . General Riemann solvers for arbitrary equations of state in the form of p = p(ρ) or p = p(ρ, e) may be found in [96].…”

Section: Appendix A1 Pressure Is Only a Function Of Density And Masmentioning

confidence: 99%

“…Instead, the equations of state for the two distinct materials will be assumed to depend on density and internal energy only, i.e. have a form p = p(ρ) or p = p(ρ, e), which may have an explicit formula or be in tabular form as in [127,96]. Material variation will be tracked using a mass fraction transport equation which al.…”

Section: Appendix a Exact Riemann Problem For Multi-materials Problemsmentioning

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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