Dynamics of phase separation of binary fluids

Ma, Wen-Jong; Maritan, Amos; Banavar, Jayanth R.; Koplik, Joel

doi:10.1103/physreva.45.r5347

Cited by 73 publications

(47 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the viscous regime (eq.2), the scaling reduces to L(T ) = A + BT where A is nonuniversal and B = bσ/η. This linear law has been reported by several groups [13,14,5] (see also [15,8,16]) but only in two recent cases [6,7] were reliable σ and η values obtained, as are needed to find b. In both of these, the offset A was significant, and the linear regime (straight part of the curve at late times) spanned much less than a decade.…”

mentioning

confidence: 69%

Tests of dynamical scaling in three-dimensional spinodal decomposition

et al. 1999

View full text Add to dashboard Cite

We simulate late-stage coarsening of a 3-D symmetric binary fluid. With reduced units l, t (with scales set by viscosity, density and surface tension) our data extends two decades in t beyond earlier work. Across at least four decades, our own and others' individual datasets (< 1 decade each) show viscous hydrodynamic scaling (l ∼ a + bt), but b is not constant between runs as this scaling demands. This betrays either the unexpected intrusion of a discretization (or molecular) lengthscale, or an exceptionally slow crossover between viscous and inertial regimes.PACS numbers: 64.75+g, 07.05. Tp, 82.20.Wt When an incompressible binary fluid mixture is quenched far below its spinodal temperature, it will phase separate into domains of different composition. For symmetric (or nearly symmetric) mixtures, these domains will, at late times, form a bicontinuous structure, with sharp, well-developed interfaces. The late-time evolution of this structure in three dimensions remains incompletely understood despite theoretical [1][2][3] experimental [4] and simulation [5][6][7][8] work over recent years.In the present work, we use the DPD (dissipative particle dynamics) simulation algorithm [9] to access length and time-scales far beyond those reached previously. (Details of the simulations will appear elsewhere [10].) When combined with other datasets [5][6][7] our results allow a severe test of the dynamical scaling ideas which underlie most theoretical treatments [1][2][3] and data analyses [4]. We conclude that dynamical scaling is in doubt, perhaps due to the intrusion of a molecular lengthscale through the physics of topological reconnection events. An alternative explanation of the results, based on a universal but extremely slow crossover, is also carefully examined.As emphasized by Siggia [1], the physics of spinodal decomposition involves capillary forces, viscous dissipation, and fluid inertia. Indeed, assuming that no other physics enters, then the parameters governing the behavior are the interfacial tension σ, fluid mass density ρ, and viscosity η. (We now specialize to 50/50 mixtures with complete symmetry of the two species. Any asymmetries in composition, thermodynamics or viscosity [11] provide additional control parameters.) From these three parameters can be constructed only one length, L 0 = η 2 /ρσ and one time T 0 = η 3 /ρσ 2 . We now define the lengthscale L(T ) of the domain structure at time T via the structure factor S(k) as [12] L = (2π) kS(k)dk/ S(k)dk −1 . The exclusion of other physics in late-stage growth then leads us to the dynamical scaling hypothesis [1,2]:where we define reduced time and length variables via l ≡ L/L 0 and t ≡ T /T 0 . Since dynamical scaling should hold only after interfaces have become sharp, and transport by molecular diffusion suppressed, we have allowed for a nonuniversal offset a in eq.1. Thereafter the scaling function f (t) should approach a universal form, the same for all (fully symmetric, deep-quenched, incompressible) binary fluid mixtures. It was argued furt...

show abstract

mentioning

confidence: 69%

Tests of dynamical scaling in three-dimensional spinodal decomposition

et al. 1999

View full text Add to dashboard Cite

show abstract

“…12 The two earlier stages have also been studied in computer simulations by using dedicated Navier-Stokes solvers, such as LB and lattice gas automata, [13][14][15] and by off-lattice particle-based methods including molecular dynamics ͑MD͒ and dissipative particle dynamics ͑DPD͒. [16][17][18][19][20][21] Other spinodal decomposition processes are less well understood than the idealized situation outlined above, although the basic principles guiding the ongoing investigations remain the same. Dynamical asymmetry of the two mixed fluids, meaning that their viscosities differ significantly or that one component shows viscoelastic behavior, explains the complex phase separation processes and the "phase inversion" phenomenon observed in polymer-solvent mixtures and colloidal suspensions.…”

Section: Introductionmentioning

confidence: 99%

Spinodal decomposition of asymmetric binary fluids in a micro-Couette geometry simulated with molecular dynamics

Thakre

Otter

Padding

et al. 2008

The Journal of Chemical Physics

View full text Add to dashboard Cite

Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. The spinodal decomposition of quenched polymer/solvent and liquid-crystal/solvent mixtures in a miniature Taylor-Couette cell has been simulated by molecular dynamics. Three stacking motifs, each reflecting the geometry and symmetry of the cell, are most abundant among the fully phase separated stationary states. At zero or low angular velocity of the inner cylindrical drum, the two segregated domains have a clear preference for the stacking with the lowest free energy and hence the smallest total interfacial tension. For high shear rates, the steady state appears to be determined by a minimum dissipation mechanism, i.e., the mixtures are likely to evolve into the stacking demanding the least mechanical power by the rotating wall. The partial slip at the polymer-solvent interfaces then gives rise to a new pattern: A stack of three concentric cylindrical shells with the viscous polymer layer sandwiched between two solvent layers. Neither of these mechanisms can explain all simulation results, as the separating mixture easily becomes kinetically trapped in a long-lived suboptimal configuration. The phase separation process is observed to proceed faster under shear than in a quiescent mixture. Related Articles

show abstract

“…Phase separation of binary fluid mixtures has also been simulated using off-lattice particle-based methods, like molecular dynamics (MD) [42,53,59] and dissipative particle dynamics (DPD) [15,41]. Because of the extremely soft interaction potentials in DPD, a linear growth regime is easily reachable in simulations, especially in the computationally less-demanding two-dimensional systems [15].…”

Section: Literature Reviewmentioning

confidence: 99%

“…Because of the extremely soft interaction potentials in DPD, a linear growth regime is easily reachable in simulations, especially in the computationally less-demanding two-dimensional systems [15]. The early MD simulations of a binary Lennard-Jones fluid by Ma et al [59] were also reported to have reached the inertial regime. Laradji et al [53] simulated a larger Lennard-Jones system and argued, based on a different analysis of the data, that the growth rate is in the viscous regime instead.…”

Section: Literature Reviewmentioning

confidence: 99%

“…Phase separation of binary fluid mixtures has also been simulated using off-lattice particlebased methods, like molecular dynamics (MD) [42,53,59] and dissipative particle dynamics (DPD) [15,41]. In the latter method, proposed a decade ago by Hoogerbrugge and Koelman [35], the hard MD potentials between atoms are replaced by extremely soft interactions between 'fluid elements', and an ingenious thermostat is introduced to make all forces consistent with Newton's third law, which also lies at the basis of hydrodynamics.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Simulations of phase separation in quiescent and sheared liquids

Thakre¹

View full text Add to dashboard Cite

Dynamics of phase separation of binary fluids

Cited by 73 publications

References 11 publications

Tests of dynamical scaling in three-dimensional spinodal decomposition

Tests of dynamical scaling in three-dimensional spinodal decomposition

Spinodal decomposition of asymmetric binary fluids in a micro-Couette geometry simulated with molecular dynamics

Simulations of phase separation in quiescent and sheared liquids

Contact Info

Product

Resources

About