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Multicomponent and multiphase modeling and simulation of reactive wetting
KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.ORCID iD: 0000-0003-3132-7252
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.
KTH, School of Engineering Sciences (SCI), Mechanics, Physicochemical Fluid Mechanics.ORCID iD: 0000-0003-3336-1462
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Physical Metallurgy.ORCID iD: 0000-0002-4521-6089
2008 (English)In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics: Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, ISSN 1063-651X, E-ISSN 1095-3787, Vol. 77, no 5, 056313- p.Article in journal (Refereed) Published
Abstract [en]

A multicomponent and multiphase model with fluid motion is developed. The model is used to study reactive wetting in the case where concentration change of the spreading liquid and the substrate occurs. With the introduction of a Gibbs energy functional, the governing equations are derived, consisting of convective concentration and phase-field equations which are coupled to the Navier-Stokes equations with surface tension forces. The solid substrate is modeled hydrodynamically with a very high viscosity. Arbitrary phase diagrams, surface energies, and typical dimensionless numbers are some input parameters into the model. An axisymmetric model with an adaptive finite element method is utilized. Numerical simulations were done revealing two stages in the wetting process. First, the convection-dominated stage where rapid spreading occurs. The dynamics of the wetting is found to match with a known hydrodynamic theory for spreading liquids. Second, the diffusion-dominated stage where we observed depression of the substrate-liquid interface and elevation of the contact line region.

Place, publisher, year, edition, pages
2008. Vol. 77, no 5, 056313- p.
Keyword [en]
Finite element method; Flow patterns; Flow simulation; Gibbs free energy; Multiphase flow; Navier Stokes equations; Governing equations; Multiphase modeling; Phase-field equations; Reactive wetting; Fluid dynamics
National Category
Materials Engineering
Identifiers
URN: urn:nbn:se:kth:diva-11085DOI: 10.1103/PhysRevE.77.056313ISI: 000256885500050Scopus ID: 2-s2.0-44649192678OAI: oai:DiVA.org:kth-11085DiVA: diva2:235445
Note

QC 20100622

Available from: 2009-09-16 Created: 2009-09-16 Last updated: 2017-12-13Bibliographically approved
In thesis
1. Diffuse-Interface Simulations of Capillary Phenomena
Open this publication in new window or tab >>Diffuse-Interface Simulations of Capillary Phenomena
2007 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Fluid flows mainly driven by capillary forces are presented in this thesis. By means of modeling and simulations, interesting dynamics in capillary-driven flows are revealed such as coalescences, breakups, precursor films, flow instabilities, rapid spreading, rigid body motions, and reactive wetting.

Diffuse-interface methods model a fluid interface as having a finite thickness endowed with physical properties such as surface tension. Two diffuse-interface models that are based on the free energy of the system are presented. The binary model, more specifically the coupled Navier-Stokes/Cahn-Hilliard equations, was used to study different two-phase flows including problems related to microfluidics. Numerical issues using this model have been addressed such as the need for mesh adaptivity and time-step restrictions. Moreover, the flexibility of this model to simulate 2D, axisymmetric, and 3D flows has been demonstrated.

The factors affecting reproducibility of microdroplet depositions performed under a liquid medium are investigated. In the deposition procedure, sample solution is dispensed from the end of a capillary by the aid of a pressure pulse onto a substrate with pillar-shaped sample anchors. In both the experimental and numerical study it was shown that the deposited volume mainly depends on the capillary-substrate distance and anchor surface wettability. Furthermore, a critical equilibrium contact angle has been identified below which reproducible depositions are facilitated.

The ternary model is developed for more complicated flows such as liquid phase sintering. With the introduction of a Gibbs energy functional, the governing equations are derived, consisting of convective concentration and phase-field equations which are coupled to the Navier-Stokes equations with surface tension forces. Arbitrary phase diagrams, surface energies, and typical dimensionless numbers are some input parameters into the model. Detailed analysis of the important capillary phenomena in liquid phase sintering such as reactive and nonreactive wetting and motion of two particles connected by a liquid bridge are presented. The dynamics of the wetting is found to match with a known hydrodynamic theory for spreading liquids. Factors affecting the equilibrium configuration of the particles such as equilibrium contact angles and volume ratios are also investigated.

Place, publisher, year, edition, pages
Stockholm: KTH, 2007. ix, 34 p.
Series
Trita-MEK, ISSN 0348-467X ; 2007:05
Keyword
capillary-driven flows, wetting, Cahn-Hilliard/Navier-Stokes system, multicomponent and multiphase flows, parallel adaptive computing
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-4402 (URN)978-91-7178-718-7 (ISBN)
Public defence
2007-06-08, Sal F2, KTH, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100823Available from: 2007-05-29 Created: 2007-05-29 Last updated: 2010-08-23Bibliographically approved
2. Phase-field modeling of surface-energy driven processes
Open this publication in new window or tab >>Phase-field modeling of surface-energy driven processes
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Surface energy plays a major role in many phenomena that are important in technological and industrial processes, for example in wetting, grain growth and sintering. In this thesis, such surface-energy driven processes are studied by means of the phase-field method. The phase-field method is often used to model mesoscale microstructural evolution in materials. It is a diffuse interface method, i.e., it considers the surface or phase boundary between two bulk phases to have a non-zero width with a gradual variation in physical properties such as energy density, composition and crystalline structure.

Neck formation and coarsening are two important diffusion-controlled features in solid-state sintering and are studied using our multiphase phase-field method. Inclusion of Navier-Stokes equation with surface-tension forces and convective phase-field equations into the model, enables simulation of reactive wetting and liquid-phase sintering. Analysis of a spreading liquid on a surface is investigated and is shown to follow the dynamics of a known hydrodynamic theory. Analysis of important capillary phenomena with wetting and motion of two particles connected by a liquid bridge are studied in view of important parameters such as contact angles and volume ratios between the liquid and solid particles.

The interaction between solute atoms and migrating grain boundaries affects the rate of recrystallization and grain growth. The phenomena is studied using a phase-field method with a concentration dependent double-well potential over the phase boundary. We will show that with a simple phase-field model it is possible to model the dynamics of grain-boundary segregation to a stationary boundary as well as solute drag on a moving boundary.

Another important issue in phase-field modeling has been to develop an effective coupling of the phase-field and CALPHAD methods. Such coulping makes use of CALPHAD's thermodynamic information with Gibbs energy function in the phase-field method. With the appropriate thermodynamic and kinetic information from CALPHAD databases, the phase-field method can predict mictrostructural evolution in multicomponent multiphase alloys. A phase-field model coupled with a TQ-interface available from Thermo-Calc is developed to study spinodal decomposition in FeCr, FeCrNi and TiC-ZrC alloys.

Place, publisher, year, edition, pages
Stockholm: KTH, Materialvetenskap, 2009. 32 p.
Keyword
Phase-field method, surface energy, solute drag, solid-state sintering, multicomponent multiphase flow, wetting, liquid-phase sintering, spinodal decomposition, CALPHAD
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-11036 (URN)978-91-7415-426-9 (ISBN)
Public defence
2009-10-02, F3, Lindstedsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100622Available from: 2009-09-16 Created: 2009-09-10 Last updated: 2010-07-19Bibliographically approved

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