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Necking after extensional filament stretching of complex fluids and soft solids (2017)
Journal Article
Hoyle, D., & Fielding, S. (2017). Necking after extensional filament stretching of complex fluids and soft solids. Journal of Non-Newtonian Fluid Mechanics, 247, 132-145. https://doi.org/10.1016/j.jnnfm.2017.06.009

We perform linear stability analysis and nonlinear slender filament simulations of extensional necking in complex fluids and soft solids, during the stress relaxation process following an interrupted strain ramp. We start by deriving analytical crite... Read More about Necking after extensional filament stretching of complex fluids and soft solids.

Criteria for extensional necking instability in complex fluids and soft solids. Part I: Imposed Hencky strain rate protocol (2016)
Journal Article
Hoyle, D. M., & Fielding, S. M. (2016). Criteria for extensional necking instability in complex fluids and soft solids. Part I: Imposed Hencky strain rate protocol. Journal of Rheology, 60(6), 1347-1375. https://doi.org/10.1122/1.4965036

We study theoretically the necking dynamics of a filament of complex fluid or soft solid in uniaxial tensile stretching at constant imposed Hencky strain rate ϵ̇ ϵ̇, by means of linear stability analysis and nonlinear (slender filament) simulations.... Read More about Criteria for extensional necking instability in complex fluids and soft solids. Part I: Imposed Hencky strain rate protocol.

Criteria for extensional necking instability in complex fluids and soft solids. Part II: Imposed tensile stress and force protocols (2016)
Journal Article
Hoyle, D. M., & Fielding, S. M. (2016). Criteria for extensional necking instability in complex fluids and soft solids. Part II: Imposed tensile stress and force protocols. Journal of Rheology, 60(6), 1377-1397. https://doi.org/10.1122/1.4965037

We study the necking of a filament of complex fluid or soft solid subject to uniaxial tensile stretching, separately under conditions of constant imposed tensile stress and constant imposed tensile force, by means of linear stability analysis and non... Read More about Criteria for extensional necking instability in complex fluids and soft solids. Part II: Imposed tensile stress and force protocols.

Shear Banding of Soft Glassy Materials in Large Amplitude Oscillatory Shear (2016)
Journal Article
Radhakrishnan, R., & Fielding, S. M. (2016). Shear Banding of Soft Glassy Materials in Large Amplitude Oscillatory Shear. Physical Review Letters, 117(18), Article 188001. https://doi.org/10.1103/physrevlett.117.188001

We study shear banding in soft glassy materials subject to a large amplitude oscillatory shear flow (LAOS). By numerical simulations of the widely used soft glassy rheology model, supplemented by more general physical arguments, we demonstrate strong... Read More about Shear Banding of Soft Glassy Materials in Large Amplitude Oscillatory Shear.

Triggers and signatures of shear banding in steady and time-dependent flows (2016)
Journal Article
Fielding, S. (2016). Triggers and signatures of shear banding in steady and time-dependent flows. Journal of Rheology, 60(5), 821-834. https://doi.org/10.1122/1.4961480

This précis is aimed as a practical field guide to situations in which shear banding might be expected in complex fluids subject to an applied shear flow. Separately for several of the most common flow protocols, it summarizes the characteristic sign... Read More about Triggers and signatures of shear banding in steady and time-dependent flows.

Shear banding in large amplitude oscillatory shear (LAOStrain and LAOStress) of polymers and wormlike micelles (2016)
Journal Article
Carter, K. A., Girkin, J. M., & Fielding, S. M. (2016). Shear banding in large amplitude oscillatory shear (LAOStrain and LAOStress) of polymers and wormlike micelles. Journal of Rheology, 60(5), Article 883. https://doi.org/10.1122/1.4960512

We investigate theoretically shear banding in large amplitude oscillatory shear (LAOS) of polymers and wormlike micelles. In LAOStrain we find banding at low frequencies and sufficiently high strain rate amplitudes in fluids for which the underlying... Read More about Shear banding in large amplitude oscillatory shear (LAOStrain and LAOStress) of polymers and wormlike micelles.

Correlation lengths in hydrodynamic models of active nematics (2016)
Journal Article
Hemingway, E., Mishra, P., Marchetti, M., & Fielding, S. (2016). Correlation lengths in hydrodynamic models of active nematics. Soft Matter, 12(38), 7943-7952. https://doi.org/10.1039/c6sm00812g

We examine the scaling with activity of the emergent length scales that control the nonequilibrium dynamics of an active nematic liquid crystal, using two popular hydrodynamic models that have been employed in previous studies. In both models we find... Read More about Correlation lengths in hydrodynamic models of active nematics.

Viscoelastic and elastomeric active matter: Linear instability and nonlinear dynamics (2016)
Journal Article
Hemingway, E., Cates, M., & Fielding, S. (2016). Viscoelastic and elastomeric active matter: Linear instability and nonlinear dynamics. Physical Review E, 93(3), Article 032702. https://doi.org/10.1103/physreve.93.032702

We consider a continuum model of active viscoelastic matter, whereby an active nematic liquid crystal is coupled to a minimal model of polymer dynamics with a viscoelastic relaxation time τC. To explore the resulting interplay between active and poly... Read More about Viscoelastic and elastomeric active matter: Linear instability and nonlinear dynamics.

Moving contact line dynamics: from diffuse to sharp interfaces (2015)
Journal Article
Kusumaatmaja, H., Hemingway, E., & Fielding, S. (2016). Moving contact line dynamics: from diffuse to sharp interfaces. Journal of Fluid Mechanics, 788, 209-227. https://doi.org/10.1017/jfm.2015.697

We reconcile two scaling laws that have been proposed in the literature for the slip length associated with a moving contact line in diffuse interface models, by demonstrating each to apply in a different regime of the ratio of the microscopic interf... Read More about Moving contact line dynamics: from diffuse to sharp interfaces.

Clustering and phase behaviour of attractive active particles with hydrodynamics (2015)
Journal Article
Matas Navarro, R., & Fielding, S. M. (2015). Clustering and phase behaviour of attractive active particles with hydrodynamics. Soft Matter, 11(38), 7525-7546. https://doi.org/10.1039/c5sm01061f

We simulate clustering, phase separation and hexatic ordering in a monolayered suspension of active squirming disks subject to an attractive Lennard-Jones-like pairwise interaction potential, taking hydrodynamic interactions between the particles ful... Read More about Clustering and phase behaviour of attractive active particles with hydrodynamics.

Age-Dependent Modes of Extensional Necking Instability in Soft Glassy Materials (2015)
Journal Article
Hoyle, D. M., & Fielding, S. M. (2015). Age-Dependent Modes of Extensional Necking Instability in Soft Glassy Materials. Physical Review Letters, 114(15), Article 158301. https://doi.org/10.1103/physrevlett.114.158301

We study the instability to necking of an initially cylindrical filament of soft glassy material subject to extensional stretching. By numerical simulation of the soft glassy rheology model and a simplified fluidity model, and by analytical predictio... Read More about Age-Dependent Modes of Extensional Necking Instability in Soft Glassy Materials.

Active Viscoelastic Matter: From Bacterial Drag Reduction to Turbulent Solids (2015)
Journal Article
Hemingway, E., Maitra, A., Banerjee, S., Marchetti, M., Ramaswamy, S., Fielding, S., & Cates, M. (2015). Active Viscoelastic Matter: From Bacterial Drag Reduction to Turbulent Solids. Physical Review Letters, 114(9), Article 098302. https://doi.org/10.1103/physrevlett.114.098302

A paradigm for internally driven matter is the active nematic liquid crystal, whereby the equations of a conventional nematic are supplemented by a minimal active stress that violates time-reversal symmetry. In practice, active fluids may have not on... Read More about Active Viscoelastic Matter: From Bacterial Drag Reduction to Turbulent Solids.

Shear banding in soft glassy materials (2014)
Journal Article
Fielding, S. M. (2014). Shear banding in soft glassy materials. Reports on Progress in Physics, 77(10), https://doi.org/10.1088/0034-4885/77/10/102601

Many soft materials, including microgels, dense colloidal emulsions, star polymers, dense packings of multilamellar vesicles, and textured morphologies of liquid crystals, share the basic 'glassy' features of structural disorder and metastability. Th... Read More about Shear banding in soft glassy materials.

Hydrodynamic suppression of phase separation in active suspensions (2014)
Journal Article
Matas-Navarro, R., Golestanian, R., Liverpool, T. B., & Fielding, S. M. (2014). Hydrodynamic suppression of phase separation in active suspensions. Physical review E: Statistical, nonlinear, and soft matter physics, 90(3), Article 032304. https://doi.org/10.1103/physreve.90.032304

We simulate with hydrodynamics a suspension of active disks squirming through a Newtonian fluid. We explore numerically the full range of squirmer area fractions from dilute to close packed and show that “motility induced phase separation,” which was... Read More about Hydrodynamic suppression of phase separation in active suspensions.

Shear banding in time-dependent flows of polymers and wormlike micelles (2013)
Journal Article
Moorcroft, R., & Fielding, S. (2014). Shear banding in time-dependent flows of polymers and wormlike micelles. Journal of Rheology, 58(1), 103-147. https://doi.org/10.1122/1.4842155

We study theoretically the formation of shear bands in time-dependent flows of polymeric and wormlike micellar surfactant fluids, focussing on the protocols of step shear stress, step shear strain (or in practice a rapid strain ramp), and shear startup... Read More about Shear banding in time-dependent flows of polymers and wormlike micelles.

Modeling the relaxation of polymer glasses under shear and elongational loads (2013)
Journal Article
Fielding, S., Moorcroft, R., Larson, R., & Cates, M. (2013). Modeling the relaxation of polymer glasses under shear and elongational loads. The Journal of Chemical Physics, 138(12), Article 12A504. https://doi.org/10.1063/1.4769253

Glassy polymers show 'strain hardening': at constant extensional load, their flow first accelerates, then arrests. Recent experiments under such loading have found this to be accompanied by a striking dip in the segmental relaxation time. This can be... Read More about Modeling the relaxation of polymer glasses under shear and elongational loads.

Criteria for Shear Banding in Time-Dependent Flows of Complex Fluids (2013)
Journal Article
Moorcroft, R., & Fielding, S. (2013). Criteria for Shear Banding in Time-Dependent Flows of Complex Fluids. Physical Review Letters, 110(8), Article 086001. https://doi.org/10.1103/physrevlett.110.086001

We study theoretically the onset of shear banding in the three most common time-dependent rheological protocols: step stress, finite strain ramp (a limit of which gives a step strain), and shear startup. By means of a linear stability analysis we pro... Read More about Criteria for Shear Banding in Time-Dependent Flows of Complex Fluids.

Simple Model for the Deformation-Induced Relaxation of Glassy Polymers (2012)
Journal Article
Fielding, S., Larson, R., & Cates, M. (2012). Simple Model for the Deformation-Induced Relaxation of Glassy Polymers. Physical Review Letters, 108(4), Article 048301. https://doi.org/10.1103/physrevlett.108.048301

Glassy polymers show “strain hardening”: at constant extensional load, their flow first accelerates, then arrests. Recent experiments have found this to be accompanied by a striking and unexplained dip in the segmental relaxation time. Here we explai... Read More about Simple Model for the Deformation-Induced Relaxation of Glassy Polymers.