Inflow/outflow with Dirichlet boundary conditions for pressure in ISPH

Kunz, P.; Hirschler, Manuel; Huber, M.; Nieken, Ulrich

doi:10.1016/j.jcp.2016.08.046

Cited by 29 publications

(12 citation statements)

References 23 publications

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“…Morris (2000) introduced the concept of modelling two-phase flows by including capillary effects in SPH. Kunz et al (2016) have validated two phase SPH considering open boundaries for the formation of bubbles during gas injection. Lattice Boltzmann methods solve the Boltzmann equation for particle density in phase space on a lattice and reproduce fluid dynamics by specific collision terms (Zhang 2011) .…”

Section: Introductionmentioning

confidence: 99%

Spontaneous imbibition in a microchannel: analytical solution and assessment of volume of fluid formulations

Pavuluri

Maes

Doster

2018

Microfluid Nanofluid

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The simulation of multi-phase flow at low capillary numbers (Ca) remains a challenge. Approximate computations of the capillary forces tend to induce parasitic currents (PC) around the interface. These PC induce additional viscous dissipation and shear forces that potentially lead to wrong calculations of the general flow dynamics. Here, we focus on the case of spontaneous imbibition in a microchannel of Hele-Shaw cell symmetry with capillarity being the only driving force. We extend the Lucas-Washburn equation to account for arbitrary viscosity ratios and assess four volume-of-fluid (VOF) formulations against the analytical solution. More specifically, we evaluate the continuum surface force (CSF) formulation, the sharp surface force (SSF) formulation, the filtered surface force (FSF) formulation and the piecewise linear interface calculation (PLIC) formulation extended by a higher order discretisation of the interface curvature through a height function with respect to accuracy, performance and heuristic parameters. We quantify PC for each formulation and investigate their impact on flow with Ca < 10 −2. The magnitude of PC are largest for CSF and are reduced two fold by SSF. FSF reduces PC considerably more but shows periodic short bursts in the velocity field. PLIC shows no PC for the studied Ca and viscosity ratios. However, it fails when a denser fluid displaces a lighter fluid. Despite PC, all formulations are accurate within 10%. PLIC is suited to serve as a reference but relies on a structured mesh and is computationally expensive. FSF requires more heuristic parameters. Together with periodic bursts, this prevents a conclusive statement on the best choice between SSF and FSF.

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Section: Introductionmentioning

confidence: 99%

Spontaneous imbibition in a microchannel: analytical solution and assessment of volume of fluid formulations

Pavuluri

Maes

Doster

2018

Microfluid Nanofluid

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“…In this work, we use the time step algorithm of Hu and Adams (2007) to enforce both velocity-divergence-free and zero-density-variation conditions at each full time step. Inflow and outflow at the open domain boundaries are realized by Dirichlet boundary conditions for the projected pressure field (Kunz et al 2016a).…”

Section: Implementation Of Surface Tension and Contact Line In Sphmentioning

confidence: 99%

Prediction of Electrolyte Distribution in Technical Gas Diffusion Electrodes: From Imaging to SPH Simulations

et al. 2020

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The performance of the gas diffusion electrode (GDE) is crucial for technical processes like chlorine-alkali electrolysis. The function of the GDE is to provide an intimate contact between gaseous reactants, the solid catalyst, and the liquid electrolyte. To accomplish this, the GDE is composed of wetting and non-wetting materials to avoid electrolyte breakthrough. Knowledge of the spatial distribution of the electrolyte in the porous structure is a prerequisite for further improvement of GDE. Therefore, the ability of the electrolyte to imbibe into the porous electrode is studied by direct numeric simulations in a reconstructed porous electrode. The information on the geometry, including the information on silver and PTFE distribution of the technical GDE, is extracted from FIB/SEM imaging including a segmentation into the different phases. Modeling of wetting phenomena inside the GDE is challenging, since surface tension and wetting of the electrolyte on silver and PTFE surfaces must be included in a physically consistent manner. Recently, wetting was modeled from first principles on the continuum scale by introducing a contact line force. Here, the newly developed contact line force model is employed to simulate two-phase flow in the solid microstructures using the smoothed particle hydrodynamics (SPH) method. In this contribution, we present the complete workflow from imaging of the GDE to dynamic SPH simulations of the electrolyte intrusion process. The simulations are used to investigate the influence of addition of non-wetting PTFE as well as the application of external pressure differences between the electrolyte and the gas phase on the intrusion process.

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“…Since the SPH scheme used in this work differs from the scheme of Hu and Adams 2006, we present simulations of a Taylor-Green vortex in "Appendix B" to show the good accuracy and convergence of our scheme. A detailed introduction into the treatment of open boundaries is given in the work of Kunz et al (2016a).…”

Section: Sph Formulation For Multi-phase Flowmentioning

confidence: 99%

“…The corresponding controller parameter values are given in Table 2. The applicability and robustness of such a pressure control have been shown by Kunz et al (2016a).…”

Section: Comparison Of the Dynamic Contact Angles Computed By Clf Modmentioning

confidence: 99%

A Two-Phase SPH Model for Dynamic Contact Angles Including Fluid–Solid Interactions at the Contact Line

2018

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The description of wetting phenomena on the continuum scale is a challenging problem, since intermolecular interactions, like van der Waals forces between liquid and solid, alter the flow field at the contact line. Recently, these effects were included in the smoothed particle hydrodynamics method by introducing a contact line force (CLF) on the continuum scale. This physically based contact line force model is employed here to simulate two-phase flow in a wide range of wetting dynamics parametrized by capillary number. In particular, dynamic contact angles at various capillary number values are calculated by CLF model and compared to measured values. We find that there is significant disagreement between simulated and measured results, specially at low wetting speeds. It is indeed expected that most of the driving force is dissipated to overcome strong liquid-solid interactions, which are not adequately accounted for in the existing CLF model. Therefore, we have extended that model to account for stick-slip (SSL) behavior of the contact line caused by solid-fluid interactions. The new SSL model results in dynamic contact angle values that are in good agreement with experimental data for the full range of wetting dynamics. Keywords Dynamic contact angle • Contact line force • Two-phase flow • Stick-slip behavior • Smoothed particle hydrodynamics (SPH) List of symbols A Arbitrary field variable B Transition function for continuous surface force at solid boundary c Color function B P. Kunz

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Inflow/outflow with Dirichlet boundary conditions for pressure in ISPH

Cited by 29 publications

References 23 publications

Spontaneous imbibition in a microchannel: analytical solution and assessment of volume of fluid formulations

Spontaneous imbibition in a microchannel: analytical solution and assessment of volume of fluid formulations

Prediction of Electrolyte Distribution in Technical Gas Diffusion Electrodes: From Imaging to SPH Simulations

A Two-Phase SPH Model for Dynamic Contact Angles Including Fluid–Solid Interactions at the Contact Line

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