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Bavand Keshavarz

Assistant Professor in the Thomas Lord Department of Mechanical Engineering and Materials Science
Thomas Lord Department of Mechanical Engineering and Materials Science

Selected Publications


Aluminosilicate colloidal gels: from the early age to the precipitation of zeolites.

Journal Article Soft matter · July 2024 Aluminosilicate hydrogels are often considered to be precursors for the crystallisation of zeolites carried out under hydrothermal conditions. The preparation of mechanically homogeneous aluminosilicate gels enables the study of these materials through bul ... Full text Cite

Mandelbrot granular raft

Journal Article Physical Review Fluids · November 1, 2023 This paper is associated with a video winner of a 2022 APS/DFD Gallery of Fluid Motion Award for work presented at the DFD Gallery of Fluid Motion. The original video is available online at the Gallery of Fluid Motion, https://doi.org/10.1103/APS.DFD.2022. ... Full text Cite

The hidden hierarchical nature of soft particulate gels

Journal Article Nature Physics · August 1, 2023 Featured Publication Soft particulate gels are composed of a small amount of particulate matter dispersed in a continuous fluid phase. The solid components assemble to form a porous matrix, providing rigidity and control of the mechanical response, despite being the minority c ... Full text Cite

Why the Cox-Merz rule and Gleissle mirror relation work: A quantitative analysis using the Wagner integral framework with a fractional Maxwell kernel

Journal Article Physics of Fluids · March 1, 2022 In this work, we mathematically derive the conditions for which empirical rheometric relations such as the Cox-Merz rule and Gleissle mirror relationship are satisfied. We consider the Wagner integral constitutive framework, which is a special limiting cas ... Full text Cite

Incorporating rheological nonlinearity into fractional calculus descriptions of fractal matter and multi-scale complex fluids

Journal Article Fractal and Fractional · December 1, 2021 In this paper, we use ideas from fractional calculus to study the rheological response of soft materials under steady-shearing flow conditions. The linear viscoelastic properties of many multi-scale complex fluids exhibit a power-law behavior that spans ov ... Full text Cite

Spectral Universality of Elastoinertial Turbulence.

Journal Article Physical review letters · August 2021 Dissolving small amounts of polymer into a Newtonian fluid can dramatically change the dynamics of transitional and turbulent flows. We investigate the spatiotemporal dynamics of a submerged jet of dilute polymer solution entering a quiescent bath of Newto ... Full text Cite

Characterizing viscoelastic properties of synthetic and natural fibers and their coatings with a torsional pendulum.

Journal Article Soft matter · May 2021 Characterizing and understanding the viscoelastic mechanical properties of natural and synthetic fibers is of great importance in many biological and industrial applications. Microscopic techniques such as micro/nano indentation have been successfully empl ... Full text Cite

Time-connectivity superposition and the gel/glass duality of weak colloidal gels.

Journal Article Proceedings of the National Academy of Sciences of the United States of America · April 2021 Featured Publication Colloidal gels result from the aggregation of Brownian particles suspended in a solvent. Gelation is induced by attractive interactions between individual particles that drive the formation of clusters, which in turn aggregate to form a space-spanning stru ... Full text Cite

Rotary atomization of newtonian and viscoelastic liquids

Journal Article Physical Review Fluids · March 1, 2020 Featured Publication We study the dynamics of fragmentation for Newtonian and viscoelastic liquids in rotary atomization. In this common industrial process centripetal acceleration destabilizes the liquid torus that forms at the rim of a spinning cup or disk due to the Rayleig ... Full text Cite

Deciphering How the Viscoelastic Properties of Mussel-Inspired Metal-Coordinate Transiently Cross-Linked Gels Dictate Their Tack Behavior.

Journal Article Langmuir : the ACS journal of surfaces and colloids · December 2019 Featured Publication In recent years, researchers have incorporated mussel-inspired metal-coordinate cross-links into various types of gels to improve their mechanical properties, particularly toughness and self-healing. However, not much is understood about how the linear mec ... Full text Cite

Viscoelastic fishbones

Journal Article Physical Review Fluids · October 24, 2019 This paper is associated with a poster winner of a 2018 APS/DFD Milton van Dyke Award for work presented at the DFD Gallery of Fluid Motion. The original poster is available from the Gallery of Fluid Motion, https://doi.org/10.1103/APS.DFD.2018.GFM.P0045. ... Full text Cite

Time-Resolved Mechanical Spectroscopy of Soft Materials via Optimally Windowed Chirps

Journal Article Physical Review X · December 6, 2018 Featured Publication The ability to measure the bulk dynamic behavior of soft materials with combined time and frequency resolution is instrumental for improving our fundamental understanding of connections between the microstructural dynamics and the macroscopic mechanical re ... Full text Cite

Computing the linear viscoelastic properties of soft gels using an optimally windowed chirp protocol

Journal Article Journal of Rheology · July 1, 2018 We use molecular dynamics simulations to investigate the linear viscoelastic response of a model three-dimensional particulate gel. The numerical simulations are combined with a novel test protocol (the optimally windowed chirp or OWCh), in which a continu ... Full text Cite

Thermal delay of drop coalescence

Journal Article Journal of Fluid Mechanics · December 25, 2017 We present the results of a combined experimental and theoretical study of drop coalescence in the presence of an initial temperature difference ΔT0 between a drop and a bath of the same liquid. We characterize experimentally the dependence of the residenc ... Full text Cite

Influence of Hydrophobicity on Polyelectrolyte Complexation

Journal Article Macromolecules · December 12, 2017 Polyelectrolyte complexes are a fascinating class of soft materials that can span the full spectrum of mechanical properties from low-viscosity fluids to glassy solids. This spectrum can be accessed by modulating the extent of electrostatic association in ... Full text Cite

Rheology as a Mechanoscopic Method to Monitor Mineralization in Hydrogels.

Journal Article Biomacromolecules · December 2017 Biominerals have been widely studied due to their unique mechanical properties, afforded by their inorganic-organic composite structure and well-controlled growth in macromolecular environments. However, a lack of suitable characterization techniques for i ... Full text Cite

Nonlinear Viscoelasticity and Generalized Failure Criterion for Polymer Gels.

Journal Article ACS macro letters · July 2017 Polymer gels behave as soft viscoelastic solids and exhibit a generic nonlinear mechanical response characterized by pronounced stiffening prior to irreversible failure, most often through macroscopic fractures. Here, we describe this scenario for a model ... Full text Cite

Ligament Mediated Fragmentation of Viscoelastic Liquids.

Journal Article Physical review letters · October 2016 Featured Publication The breakup and atomization of complex fluids can be markedly different than the analogous processes in a simple Newtonian fluid. Atomization of paint, combustion of fuels containing antimisting agents, as well as physiological processes such as sneezing a ... Full text Cite

Governing Principles of Alginate Microparticle Synthesis with Centrifugal Forces

Journal Article Langmuir · July 19, 2016 A controlled synthesis of polymeric particles is becoming increasingly important because of emerging applications ranging from medical diagnostics to self-assembly. Centrifugal synthesis of hydrogel microparticles is a promising method, combining rapid par ... Full text Cite

Micro-scale extensional rheometry using hyperbolic converging/diverging channels and jet breakup

Journal Article Biomicrofluidics · July 1, 2016 Understanding the elongational rheology of dilute polymer solutions plays an important role in many biological and industrial applications ranging from microfluidic lab-on-a-chip diagnostics to phenomena such as fuel atomization and combustion. Making quan ... Full text Cite

Aluminosilicate colloidal gels: from the early age to the precipitation of zeolites.

Journal Article Soft matter · July 2024 Aluminosilicate hydrogels are often considered to be precursors for the crystallisation of zeolites carried out under hydrothermal conditions. The preparation of mechanically homogeneous aluminosilicate gels enables the study of these materials through bul ... Full text Cite

Mandelbrot granular raft

Journal Article Physical Review Fluids · November 1, 2023 This paper is associated with a video winner of a 2022 APS/DFD Gallery of Fluid Motion Award for work presented at the DFD Gallery of Fluid Motion. The original video is available online at the Gallery of Fluid Motion, https://doi.org/10.1103/APS.DFD.2022. ... Full text Cite

The hidden hierarchical nature of soft particulate gels

Journal Article Nature Physics · August 1, 2023 Featured Publication Soft particulate gels are composed of a small amount of particulate matter dispersed in a continuous fluid phase. The solid components assemble to form a porous matrix, providing rigidity and control of the mechanical response, despite being the minority c ... Full text Cite

Why the Cox-Merz rule and Gleissle mirror relation work: A quantitative analysis using the Wagner integral framework with a fractional Maxwell kernel

Journal Article Physics of Fluids · March 1, 2022 In this work, we mathematically derive the conditions for which empirical rheometric relations such as the Cox-Merz rule and Gleissle mirror relationship are satisfied. We consider the Wagner integral constitutive framework, which is a special limiting cas ... Full text Cite

Incorporating rheological nonlinearity into fractional calculus descriptions of fractal matter and multi-scale complex fluids

Journal Article Fractal and Fractional · December 1, 2021 In this paper, we use ideas from fractional calculus to study the rheological response of soft materials under steady-shearing flow conditions. The linear viscoelastic properties of many multi-scale complex fluids exhibit a power-law behavior that spans ov ... Full text Cite

Spectral Universality of Elastoinertial Turbulence.

Journal Article Physical review letters · August 2021 Dissolving small amounts of polymer into a Newtonian fluid can dramatically change the dynamics of transitional and turbulent flows. We investigate the spatiotemporal dynamics of a submerged jet of dilute polymer solution entering a quiescent bath of Newto ... Full text Cite

Characterizing viscoelastic properties of synthetic and natural fibers and their coatings with a torsional pendulum.

Journal Article Soft matter · May 2021 Characterizing and understanding the viscoelastic mechanical properties of natural and synthetic fibers is of great importance in many biological and industrial applications. Microscopic techniques such as micro/nano indentation have been successfully empl ... Full text Cite

Time-connectivity superposition and the gel/glass duality of weak colloidal gels.

Journal Article Proceedings of the National Academy of Sciences of the United States of America · April 2021 Featured Publication Colloidal gels result from the aggregation of Brownian particles suspended in a solvent. Gelation is induced by attractive interactions between individual particles that drive the formation of clusters, which in turn aggregate to form a space-spanning stru ... Full text Cite

Rotary atomization of newtonian and viscoelastic liquids

Journal Article Physical Review Fluids · March 1, 2020 Featured Publication We study the dynamics of fragmentation for Newtonian and viscoelastic liquids in rotary atomization. In this common industrial process centripetal acceleration destabilizes the liquid torus that forms at the rim of a spinning cup or disk due to the Rayleig ... Full text Cite

Deciphering How the Viscoelastic Properties of Mussel-Inspired Metal-Coordinate Transiently Cross-Linked Gels Dictate Their Tack Behavior.

Journal Article Langmuir : the ACS journal of surfaces and colloids · December 2019 Featured Publication In recent years, researchers have incorporated mussel-inspired metal-coordinate cross-links into various types of gels to improve their mechanical properties, particularly toughness and self-healing. However, not much is understood about how the linear mec ... Full text Cite

Viscoelastic fishbones

Journal Article Physical Review Fluids · October 24, 2019 This paper is associated with a poster winner of a 2018 APS/DFD Milton van Dyke Award for work presented at the DFD Gallery of Fluid Motion. The original poster is available from the Gallery of Fluid Motion, https://doi.org/10.1103/APS.DFD.2018.GFM.P0045. ... Full text Cite

Time-Resolved Mechanical Spectroscopy of Soft Materials via Optimally Windowed Chirps

Journal Article Physical Review X · December 6, 2018 Featured Publication The ability to measure the bulk dynamic behavior of soft materials with combined time and frequency resolution is instrumental for improving our fundamental understanding of connections between the microstructural dynamics and the macroscopic mechanical re ... Full text Cite

Computing the linear viscoelastic properties of soft gels using an optimally windowed chirp protocol

Journal Article Journal of Rheology · July 1, 2018 We use molecular dynamics simulations to investigate the linear viscoelastic response of a model three-dimensional particulate gel. The numerical simulations are combined with a novel test protocol (the optimally windowed chirp or OWCh), in which a continu ... Full text Cite

Thermal delay of drop coalescence

Journal Article Journal of Fluid Mechanics · December 25, 2017 We present the results of a combined experimental and theoretical study of drop coalescence in the presence of an initial temperature difference ΔT0 between a drop and a bath of the same liquid. We characterize experimentally the dependence of the residenc ... Full text Cite

Influence of Hydrophobicity on Polyelectrolyte Complexation

Journal Article Macromolecules · December 12, 2017 Polyelectrolyte complexes are a fascinating class of soft materials that can span the full spectrum of mechanical properties from low-viscosity fluids to glassy solids. This spectrum can be accessed by modulating the extent of electrostatic association in ... Full text Cite

Rheology as a Mechanoscopic Method to Monitor Mineralization in Hydrogels.

Journal Article Biomacromolecules · December 2017 Biominerals have been widely studied due to their unique mechanical properties, afforded by their inorganic-organic composite structure and well-controlled growth in macromolecular environments. However, a lack of suitable characterization techniques for i ... Full text Cite

Nonlinear Viscoelasticity and Generalized Failure Criterion for Polymer Gels.

Journal Article ACS macro letters · July 2017 Polymer gels behave as soft viscoelastic solids and exhibit a generic nonlinear mechanical response characterized by pronounced stiffening prior to irreversible failure, most often through macroscopic fractures. Here, we describe this scenario for a model ... Full text Cite

Ligament Mediated Fragmentation of Viscoelastic Liquids.

Journal Article Physical review letters · October 2016 Featured Publication The breakup and atomization of complex fluids can be markedly different than the analogous processes in a simple Newtonian fluid. Atomization of paint, combustion of fuels containing antimisting agents, as well as physiological processes such as sneezing a ... Full text Cite

Governing Principles of Alginate Microparticle Synthesis with Centrifugal Forces

Journal Article Langmuir · July 19, 2016 A controlled synthesis of polymeric particles is becoming increasingly important because of emerging applications ranging from medical diagnostics to self-assembly. Centrifugal synthesis of hydrogel microparticles is a promising method, combining rapid par ... Full text Cite

Micro-scale extensional rheometry using hyperbolic converging/diverging channels and jet breakup

Journal Article Biomicrofluidics · July 1, 2016 Understanding the elongational rheology of dilute polymer solutions plays an important role in many biological and industrial applications ranging from microfluidic lab-on-a-chip diagnostics to phenomena such as fuel atomization and combustion. Making quan ... Full text Cite

Drop impact and capture on a thin flexible fiber

Journal Article Soft Matter · October 1, 2015 When a drop impacts a thin fiber, a critical impact speed can be defined, below which the drop is entirely captured by the fiber, and above which the drop pinches-off and fractures. We discuss here the capture dynamics of both inviscid and viscous drops on ... Full text Cite

Studying the effects of elongational properties on atomization of weakly viscoelastic solutions using Rayleigh Ohnesorge Jetting Extensional Rheometry (ROJER)

Journal Article Journal of Non-Newtonian Fluid Mechanics · August 1, 2015 The extensional rheological properties of dilute polymer solutions play a dominant role in many commercial processes such as air-assisted atomization. This is a high deformation rate process important in application of diverse materials such as paints, fer ... Full text Cite

The rheology of aqueous solutions of ethyl hydroxy-ethyl cellulose (EHEC) and its hydrophobically modified analogue (hmEHEC): Extensional flow response in capillary break-up, jetting (ROJER) and in a cross-slot extensional rheometer

Journal Article Soft Matter · April 28, 2015 Cellulose derivatives containing associating hydrophobic groups along their hydrophilic backbone are used as rheology modifiers in the formulation of water-based spray paints, medicinal sprays, cosmetics and printable inks. Jetting and spraying application ... Full text Cite

Elastic liquid jet impaction on a high-speed moving surface

Journal Article AIChE Journal · November 1, 2012 In the railroad industry a friction-modifying non-Newtonian liquid, showing elastic behavior, may be applied to the rail in the form of a liquid jet. The interaction of this elastic liquid jet and the moving surface-specifically whether it splashes or adhe ... Full text Cite

Newtonian liquid jet impaction on a high-speed moving surface

Journal Article International Journal of Heat and Fluid Flow · December 1, 2011 In the railroad industry a friction modifying agent may be applied to the rail or wheel in the form of a liquid jet. In this mode of application the interaction between the high-speed liquid jet and a fast moving surface is important. Seven different Newto ... Full text Cite