A model for complex flows of soft glassy materials with application to flows through fixed fiber beds

Handle URI:
http://hdl.handle.net/10754/597309
Title:
A model for complex flows of soft glassy materials with application to flows through fixed fiber beds
Authors:
Sarkar, Arijit; Koch, Donald L.
Abstract:
© 2015 The Society of Rheology. The soft glassy rheology (SGR) model has successfully described the time dependent simple shear rheology of a broad class of complex fluids including foams, concentrated emulsions, colloidal glasses, and solvent-free nanoparticle-organic hybrid materials (NOHMs). The model considers a distribution of mesoscopic fluid elements that hop from trap to trap at a rate which is enhanced by the work done to strain the fluid element. While an SGR fluid has a broad exponential distribution of trap energies, the rheology of NOHMs is better described by a narrower energy distribution and we consider both types of trap energy distributions in this study. We introduce a tensorial version of these models with a hopping rate that depends on the orientation of the element relative to the mean stress field, allowing a range of relative strengths of the extensional and simple shear responses of the fluid. As an application of these models we consider the flow of a soft glassy material through a dilute fixed bed of fibers. The dilute fixed bed exhibits a range of local linear flows which alternate in a chaotic manner with time in a Lagrangian reference frame. It is amenable to an analytical treatment and has been used to characterize the strong flow response of many complex fluids including fiber suspensions, dilute polymer solutions and emulsions. We show that the accumulated strain in the fluid elements has an abrupt nonlinear growth at a Deborah number of order one in a manner similar to that observed for polymer solutions. The exponential dependence of the hopping rate on strain leads to a fluid element deformation that grows logarithmically with Deborah number at high Deborah numbers. SGR fluids having a broad range of trap energies flowing through fixed beds can exhibit a range of rheological behaviors at small Deborah numbers ranging from a yield stress, to a power law response and finally to Newtonian behavior.
Citation:
Sarkar A, Koch DL (2015) A model for complex flows of soft glassy materials with application to flows through fixed fiber beds. J Rheol 59: 1487–1505. Available: http://dx.doi.org/10.1122/1.4934367.
Publisher:
Society of Rheology
Journal:
Journal of Rheology
KAUST Grant Number:
KUS-C1-018-02
Issue Date:
Nov-2015
DOI:
10.1122/1.4934367
Type:
Article
ISSN:
0148-6055; 1520-8516
Sponsors:
The authors thank E. S. G. Shaqfeh for helpful discussions related to the formulation of the constitutive model. This work was supported by Award No. KUS-C1-018-02 made by the King Abdullah University of Science and Technology (KAUST).
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Full metadata record

DC FieldValue Language
dc.contributor.authorSarkar, Arijiten
dc.contributor.authorKoch, Donald L.en
dc.date.accessioned2016-02-25T12:30:22Zen
dc.date.available2016-02-25T12:30:22Zen
dc.date.issued2015-11en
dc.identifier.citationSarkar A, Koch DL (2015) A model for complex flows of soft glassy materials with application to flows through fixed fiber beds. J Rheol 59: 1487–1505. Available: http://dx.doi.org/10.1122/1.4934367.en
dc.identifier.issn0148-6055en
dc.identifier.issn1520-8516en
dc.identifier.doi10.1122/1.4934367en
dc.identifier.urihttp://hdl.handle.net/10754/597309en
dc.description.abstract© 2015 The Society of Rheology. The soft glassy rheology (SGR) model has successfully described the time dependent simple shear rheology of a broad class of complex fluids including foams, concentrated emulsions, colloidal glasses, and solvent-free nanoparticle-organic hybrid materials (NOHMs). The model considers a distribution of mesoscopic fluid elements that hop from trap to trap at a rate which is enhanced by the work done to strain the fluid element. While an SGR fluid has a broad exponential distribution of trap energies, the rheology of NOHMs is better described by a narrower energy distribution and we consider both types of trap energy distributions in this study. We introduce a tensorial version of these models with a hopping rate that depends on the orientation of the element relative to the mean stress field, allowing a range of relative strengths of the extensional and simple shear responses of the fluid. As an application of these models we consider the flow of a soft glassy material through a dilute fixed bed of fibers. The dilute fixed bed exhibits a range of local linear flows which alternate in a chaotic manner with time in a Lagrangian reference frame. It is amenable to an analytical treatment and has been used to characterize the strong flow response of many complex fluids including fiber suspensions, dilute polymer solutions and emulsions. We show that the accumulated strain in the fluid elements has an abrupt nonlinear growth at a Deborah number of order one in a manner similar to that observed for polymer solutions. The exponential dependence of the hopping rate on strain leads to a fluid element deformation that grows logarithmically with Deborah number at high Deborah numbers. SGR fluids having a broad range of trap energies flowing through fixed beds can exhibit a range of rheological behaviors at small Deborah numbers ranging from a yield stress, to a power law response and finally to Newtonian behavior.en
dc.description.sponsorshipThe authors thank E. S. G. Shaqfeh for helpful discussions related to the formulation of the constitutive model. This work was supported by Award No. KUS-C1-018-02 made by the King Abdullah University of Science and Technology (KAUST).en
dc.publisherSociety of Rheologyen
dc.titleA model for complex flows of soft glassy materials with application to flows through fixed fiber bedsen
dc.typeArticleen
dc.identifier.journalJournal of Rheologyen
dc.contributor.institutionSchool of Chemical and Biomolecular Engineering, Cornell University, 120 Olin Hall, Ithaca, New York 14853-5201en
kaust.grant.numberKUS-C1-018-02en
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