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Wettlaufer, John
Publications (5 of 5) Show all publications
Marath, N. K. & Wettlaufer, J. (2019). Hydrodynamic interactions and the diffusivity of spheroidal particles. Journal of Chemical Physics, 151(2), Article ID 024107.
Open this publication in new window or tab >>Hydrodynamic interactions and the diffusivity of spheroidal particles
2019 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 151, no 2, article id 024107Article in journal (Refereed) Published
Abstract [en]

It is intuitive that the diffusivity of an isolated particle differs from those in a monodisperse suspension, in which hydrodynamic interactions between the particles are operative. Batchelor [J. Fluid Mech. 74, 1-29 (1976) and J. Fluid Mech. 131, 155-175 (1983)] calculated how hydrodynamic interactions influenced the diffusivity of a dilute suspension of spherical particles, and Russel et al. [Colloidal Dispersions (Cambridge University Press, 1991)] and Brady [J. Fluid Mech. 272, 109-134 (1994)] treated nondilute (higher particle volume fraction) suspensions. Although most particles lack perfect sphericity, little is known about the effects of hydrodynamic interactions on the diffusivity of spheroidal particles, which are the simplest shapes that can be used to model anisotropic particles. Here, we calculate the effects of hydrodynamic interactions on the translational and rotational diffusivities of spheroidal particles of arbitrary aspect ratio in dilute monodisperse suspensions. We find that the translational and rotational diffusivities of prolate spheroids are more sensitive to eccentricity than for oblate spheroids. The origin of the hydrodynamic anisotropy is that found in the stresslet field for the induced-dipole interaction. However, in the dilute limit, the effects of anisotropy are at the level of a few percent. These effects have influence on a vast range of settings, from partially frozen colloidal suspensions to the dynamics of cytoplasm.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-261341 (URN)10.1063/1.5096764 (DOI)000486055700009 ()31301717 (PubMedID)2-s2.0-85068759215 (Scopus ID)
Note

QC 20191007

Available from: 2019-10-07 Created: 2019-10-07 Last updated: 2019-10-07Bibliographically approved
Wettlaufer, J. (2019). Surface phase transitions in ice: From fundamental interactions to applications. Philosophical Transactions. Series A: Mathematical, physical, and engineering science, 377(2146), Article ID 20180261.
Open this publication in new window or tab >>Surface phase transitions in ice: From fundamental interactions to applications
2019 (English)In: Philosophical Transactions. Series A: Mathematical, physical, and engineering science, ISSN 1364-503X, E-ISSN 1471-2962, Vol. 377, no 2146, article id 20180261Article in journal (Refereed) Published
Abstract [en]

Interfaces divide all phases of matter and yet in most practical settings it is tempting to ignore their energies and the associated implications. There are many reasons for this, not the least of which is the introduction of a new pair of canonically conjugate variables-interfacial energy and its counterpart the surface area. A key set of questions surrounding the treatment of multiphase flows concerns how and when we must account for such effects. I begin this discussion with an abbreviated review of the basic theory of lower-dimensional phase transitions and describe a range of situations in which the bulk behaviour of a two-phase (and in some cases twocomponent) system is dominated by surface effects. Then I discuss a number of settings in which the bulk and surface behaviour can interact on equal footing. These can include the dynamic and thermodynamic behaviour of floating sea ice, the freezing and drying of colloidal suspensions (such as soil) and the mechanisms of protoplanetesimal formation by inter-particle collisions in accretion discs. This article is part of the theme issue 'The physics and chemistry of ice: Scaffolding across scales, from the viability of life to the formation of planets'. © 2019 Royal Society Publishing. All rights reserved.

Place, publisher, year, edition, pages
Royal Society Publishing, 2019
Keywords
Ice physics, Phase transitions, Surfaces, Scaffolds, Sea ice, Suspensions (fluids), Two phase flow, Accretion discs, Colloidal suspensions, Conjugate variables, Inter-particle collision, Set of questions, Surface effect, Surface phase transitions, Thermodynamic behaviour
National Category
Other Natural Sciences
Identifiers
urn:nbn:se:kth:diva-252514 (URN)10.1098/rsta.2018.0261 (DOI)000466382900007 ()2-s2.0-85064852836 (Scopus ID)
Note

QC 20190710

Available from: 2019-07-10 Created: 2019-07-10 Last updated: 2019-07-10Bibliographically approved
Toppaladoddi, S. & Wettlaufer, J. (2019). The combined effects of shear and buoyancy on phase boundary stability. Journal of Fluid Mechanics, 868, 648-665
Open this publication in new window or tab >>The combined effects of shear and buoyancy on phase boundary stability
2019 (English)In: Journal of Fluid Mechanics, ISSN 0022-1120, E-ISSN 1469-7645, Vol. 868, p. 648-665Article in journal (Refereed) Published
Abstract [en]

We study the effects of externally imposed shear and buoyancy driven flows on the stability of a solid-liquid interface. A linear stability analysis of shear and buoyancy-driven flow of a melt over its solid phase shows that buoyancy is the only destabilizing factor and that the regime of shear flow here, by inhibiting vertical motions and hence the upward heat flux, stabilizes the system. It is also shown that all perturbations to the solid-liquid interface decay at a very modest shear flow strength. However, at much larger shear-flow strength, where flow instabilities coupled with buoyancy might enhance vertical motions, a re-entrant instability may arise.

Place, publisher, year, edition, pages
CAMBRIDGE UNIV PRESS, 2019
Keywords
buoyancy-driven instability, morphological instability, solidification, melting, LVES RT, 1971, JOURNAL OF CRYSTAL GROWTH, V8, P13
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-251270 (URN)10.1017/jfm.2019.153 (DOI)000465313700001 ()2-s2.0-85064854380 (Scopus ID)
Note

QC 20190513

Available from: 2019-05-13 Created: 2019-05-13 Last updated: 2019-05-29Bibliographically approved
Pramanik, S. & Wettlaufer, J. (2017). Confinement effects in premelting dynamics. Physical review. E, 96(5), Article ID 052801.
Open this publication in new window or tab >>Confinement effects in premelting dynamics
2017 (English)In: Physical review. E, ISSN 2470-0045, E-ISSN 2470-0053, Vol. 96, no 5, article id 052801Article in journal (Refereed) Published
Abstract [en]

We examine the effects of confinement on the dynamics of premelted films driven by thermomolecular pressure gradients. Our approach is to modify a well-studied setting in which the thermomolecular pressure gradient is driven by a temperature gradient parallel to an interfacially premelted elastic wall. The modification treats the increase in viscosity associated with the thinning of films, studied in a wide variety of materials, using a power law and we examine the consequent evolution of the confining elastic wall. We treat (1) a range of interactions that are known to underlie interfacial premelting and (2) a constant temperature gradient wherein the thermomolecular pressure gradient is a constant. The difference between the cases with and without the proximity effect arises in the volume flux of premelted liquid. The proximity effect increases the viscosity as the film thickness decreases thereby requiring the thermomolecular pressure driven flux to be accommodated at higher temperatures where the premelted film thickness is the largest. Implications for experiment and observations of frost heave are discussed.

Place, publisher, year, edition, pages
American Physical Society, 2017
Keywords
Film thickness, Films, Gas dynamics, Pressure, Pressure gradient, Temperature, Thermal gradients, Viscosity, Confinement effects, Constant temperature, Elastic walls, Frost heave, Pre-melting, Premelted films, Proximity effects, Thermomolecular pressure, Thermodynamics
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-227146 (URN)10.1103/PhysRevE.96.052801 (DOI)000414961000010 ()2-s2.0-85034013051 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20180502

Available from: 2018-05-02 Created: 2018-05-02 Last updated: 2019-10-18Bibliographically approved
Mancarella, F. & Wettlaufer, J. (2017). Surface tension and a self-consistent theory of soft composite solids with elastic inclusions. Soft Matter, 13(5), 945-955
Open this publication in new window or tab >>Surface tension and a self-consistent theory of soft composite solids with elastic inclusions
2017 (English)In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 13, no 5, p. 945-955Article in journal (Refereed) Published
Abstract [en]

The importance of surface tension effects is being recognized in the context of soft composite solids, where they are found to significantly affect the mechanical properties, such as the elastic response to an external stress. It has recently been discovered that Eshelby's inclusion theory breaks down when the inclusion size approaches the elastocapillary length L ≡ γ/E, where γ is the inclusion/host surface tension and E is the host Young's modulus. Extending our recent results for liquid inclusions, here we model the elastic behavior of a non-dilute distribution of isotropic elastic spherical inclusions in a soft isotropic elastic matrix, subject to a prescribed infinitesimal far-field loading. Within our framework, the composite stiffness is uniquely determined by the elastocapillary length L, the spherical inclusion radius R, and the stiffness contrast parameter C, which is the ratio of the inclusion to the matrix stiffness. We compare the results with those from the case of liquid inclusions, and we derive an analytical expression for elastic cloaking of the composite by the inclusions. Remarkably, we find that the composite stiffness is influenced significantly by surface tension even for inclusions two orders of magnitude more stiff than the host matrix. Finally, we show how to simultaneously determine the surface tension and the inclusion stiffness using two independent constraints provided by global and local measurements.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2017
Keywords
Composite materials, Elastic moduli, Stiffness, Surface tension, Analytical expressions, Composite stiffness, Contrast parameter, Elastic spherical inclusion, Eshelby's inclusion, Orders of magnitude, Spherical inclusion, Surface tension effects, Stiffness matrix
National Category
Physical Sciences Chemical Sciences Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-207387 (URN)10.1039/c6sm02396g (DOI)000395390400006 ()2-s2.0-85011407673 (Scopus ID)
Note

Funding details: 638-2013-9243, VR, Vetenskapsrådet; Funding text: The authors thank R. W. Style for his encouragement to examine this system. FM and JSW acknowledge Swedish Research Council Grant No. 638-2013-9243. JSW also acknowledges a Royal Society Wolfson Research Merit Award.

QC 20170609

Available from: 2017-06-09 Created: 2017-06-09 Last updated: 2017-06-09Bibliographically approved
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