Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session Y25: Constraint-based Rheology of Dense Suspensions and Granular Materials IIRecordings Available
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Sponsoring Units: DSOFT GSNP Chair: Safa Jamali, Northeastern University Room: McCormick Place W-187A |
Friday, March 18, 2022 8:00AM - 8:12AM |
Y25.00001: Shear thickening and jamming of bidisperse dense suspensions Abhinendra Singh, Abhishek K Sharma, Juan De Pablo, Heinrich M Jaeger The mechanism of shear thickening in dense suspensions has been linked to a stress-controlled transition from a lubricated "frictionless'' to an unlubricated "frictional'' rheology. Recent particle simulations that constrain the relative motion between particles have been successful to reproduce both the discontinuous shear thickening (DST) and shear jamming (SJ) observed experimentally for rough and smooth particles. However, so far only monodisperse or weakly bidisperse cases are considered. We perform numerical simulations at a fixed volume fraction varying size ratio of particle radii (up to 1:12) and volume fraction of small particles. We find that at a constant volume fraction, the critical shear stress and frictional viscosity can be tuned through the size ratio and volume fraction of small particles. In this presentation, we will investigate these bidisperse systems' network characteristics and microstructure to disentangle the contribution of various types of contacts on the simulated rheology suspensions. |
Friday, March 18, 2022 8:12AM - 8:24AM |
Y25.00002: Running on fluid: The impact-induced hardening on dense suspensions Pradipto -, Hisao Hayakawa We simulate the impact-induced hardening in dense suspensions with the lattice Boltzmann method that incorporates the contact between suspended particles and the free surface of the suspension. First, we analyze the rebound motion of a free-falling spherical impactor on top of the suspensions, how the frictional interactions between suspended particles affect the rebound, and how to characterize the topological structure of the dynamically jammed region beneath the impactor [1]. Then, we discuss the connection between the rebound motion, the impact speed, and the maximum force acting on the impactor, by proposing a phenomenology that can recover the viscoelastic response of the impactor during the impact [2]. |
Friday, March 18, 2022 8:24AM - 8:36AM |
Y25.00003: Constraint-based approach towards debris flow rheology Shravan Pradeep, Paulo Arratia, Douglas J Jerolmack, Robert Kostynick, Thomas Dunne Debris flows are dense, fast-flowing suspensions that form when intense rainfall fluidizes soil on steep mountain hillslopes. Such flows are associated with complex fluid-particle mixtures with particulates ranging from clay to gravel to ash, resulting in a diverse range of interparticle interactions (friction, cohesion, lubrication etc.) giving rise to correspondingly rich rheological behaviors under external natural disturbances. Here we use a constraint-based approach to interpret how interparticle interactions give rise to complex flow curves, and apply this framework to synthetic and natural debris-flow suspensions. Suspensions of sand and kaolinite powder - generated over a range of volume fractions (φ) are used as an idealized model for debris flows, where interparticle interactions can be tuned with water chemistry. We also examine soils that served as the source of deadly post-wildfire debris flows in Montecito, California in 2018. This allows us to test whether results obtained for idealized suspensions may be extended to highly heterogeneous natural materials. Experimental flow curves can be fully explained by a loosening of cohesive contraints with increasing stress (σ), where the yielding and shear-jamming states are separated by distinct stress scales. The flowing and jammed regions of each suspension are demarcated by a line in σ-φ phase space. We use this finding to propose a rheological state diagram for debris flows, and map our data and additional debris-flow data from the literature onto this diagram. |
Friday, March 18, 2022 8:36AM - 8:48AM Withdrawn |
Y25.00004: Probing of experimental boundary conditions for theoretical non-local models Nathalie M Vriend, Rebecca N Poon, Ben McMillan, Benjamin M Jackson Non-local phenomena in granular flows are evident in experimental data, but are difficult to explain with conventional granular theories. Recently, the concept of granular fluidity has been central in the development of new non-local constitutive equations, but experimental validation remains sparse. Specifically, the origin of the fluidity on a microscopic, single-particle level is still unproven. In this work, we present an experimental validation of the microscopic definition of the granular fluidity. Most importantly, we show that boundary conditions play a major role and influence the specific form of the granular fluidity model. |
Friday, March 18, 2022 8:48AM - 9:00AM |
Y25.00005: Rigid Cluster Decomposition of Dense Suspension Flows Michael R Van der Naald, Abhinendra Singh, Toka T Eid, Kenan Tang, Heinrich M Jaeger, Juan De Pablo
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Friday, March 18, 2022 9:00AM - 9:12AM |
Y25.00006: A continuum model for the bulldozing of an immersed granular material in a confined geometry Liam Morrow The flow of immersed granular materials in confined geometries is difficult to characterise due to the complex interactions among the grains, between the grains and the ambient liquid, and between both materials and the walls. Here, we present a reduced-order continuum model for the bulldozing of an immersed, sedimented granular material by a rigid piston in a fluid-filled gap between two parallel plates. This scenario has been studied previously using ad-hoc models and discrete-element simulations. In our continuum approach, the granular pile and the overlying fluid layer evolve as coupled thin films. We model the solid phase as a dense, viscous porous material that experiences Coulomb-like friction along the walls. Conservation of mass and momentum lead to a linear elliptic equation for the local velocity of the grains that is coupled with a nonlinear conservation law for the height of the granular pile. We solve our model numerically for a variety of different scenarios in order to develop insight into the interactions between wall friction, internal viscous-like stresses, and fluid flow both above and through the pile. |
Friday, March 18, 2022 9:12AM - 9:24AM |
Y25.00007: Emergent Elasticity in Jammed Solids: Constraints and a Gauge Theory of Non-Brownian Rheology Jishnu N Nampoothiri, Michael D'Eon, Kabir Ramola, Subhro Bhattacharjee, Bulbul Chakraborty There is emerging consensus that shear-thickening in dense suspensions is controlled by the kinetic constraints imposed on the motion of grains: transitions from lubricated to frictional or adhesive contacts change these constraints. A continuum theory of rheology must account correctly for such kinetic constraints while incorporating microscale information about the structural and contact disorder. Recently, we have succeeded in constructing such a theoretical framework for the elasticity of jammed solids [Phys. Rev. Lett. 125, 118002 (2020)]. Central to this theory is a gauge theoretic structure that arises from the lack of a unique zero-stress reference state, and, the local constraints of mechanical equilibrium on each grain. The latter serves as a “Gauss’s law’’ for a tensorial electric field, which maps on to the stress tensor, and the elastic moduli emerge from the microscopic properties of the networks. The complete gauge-theoretic structure allows for flowing states through the presence of the analog of a magnetic sector to the electric one, which describes static jammed states. In this talk, we will discuss shear-thickening rheology from the perspective of this gauge theory. This work has been supported by NSF-CBET 1916877 and NSF-DMR 2026834. |
Friday, March 18, 2022 9:24AM - 9:36AM |
Y25.00008: Controlling shear thickening transition in confined dense suspensions through boundary stresses Haitao HU, Yiqiu Zhao, Qin Xu We experimentally investigate the shear thickening behaviors of a dense granular suspension in a confined geometry. Our study specifically focuses on the slow relaxation dynamics and stress fluctuations near the thickening onset. By systematically varying the measuring time at each shear rate, we observe a dramatic change of the shear thickening behaviors in a confined geometry. With a gradual increase of the system size, this waiting-time dependence of suspension rheology will reduce and eventually disappear. By combining steady state rheological measurements with in-situ rheo-optical imaging, we quantitatively show that strong shear thickening response in a confined suspension is associated with a significant enhancement of both temporal stress fluctuations and spatial stress inhomogeneities. Further increase of shear rate or shear stress beyond the onset, however, will reduce the stress fluctuations. Our results clearly demonstrated how to control the statistical mechanics and shear rheology of confined suspensions through boundary stresses. |
Friday, March 18, 2022 9:36AM - 9:48AM |
Y25.00009: Correlation between rheology of charged particle suspensions and microscopic interactions and dynamics HongRui He, Yan Fang, Qiming He, Jiang Zhang, Xiao-Min Lin, Jelena Dinic, Matthew V Tirrell, Suresh Narayanan, Wei Chen Colloidal gels aggregated from charged particles with attractive or repulsive forces form a rigid and fragile network that could easily yield, transforming from a solid to a more prominent liquid-like characteristics under weak external forces. Such materials are promising for applications in everyday life, including battery electrolyte, drug design, enhanced oil recovery, and food products. To improve the efficiency and extent of these applications, the mechanical properties of the colloidal gel such as yielding could be tuned by controlling the surface interaction of individual particles and ionic conditions in the solvent. Consequently, it is imperative to understand the fundamental relationship between the macroscopic properties and microscopic behavior. X-ray photon correlation spectroscopy (XPCS) carried out in conjunction with in situ rheology (Rheo-XPCS) is ideally suited to probe fluctuation dynamics at the relevant length scales (10-300 nm). XPCS measurements of the colloidal gels reveal novel microscopic dynamic features during creep and relaxation thereafter. The yielding transitions observed under applied stresses are consistently correlated with the strain and shear in rheological measurements. The influence on creep response and variations to the correlation function from the addition of salts with different valences to the colloidal gel is also revealed. The results connect the microscopic dynamics of particles to the macroscopic properties of the system establishing new perspectives on understanding dynamic behaviors of the colloid suspension under external forces. |
Friday, March 18, 2022 9:48AM - 10:00AM |
Y25.00010: Relationships among structure, memory, and flow in sheared disordered materials Larry Galloway, Erin G Teich, Xiaoguang Ma, Christoph Kammer, Ian R Graham, Nathan C Keim, Celia Reina, Douglas J Jerolmack, Arjun G Yodh, Paulo Arratia How soft materials yield is a question of fundamental interest to material engineers and rheologists alike. Often, we model complex fluids from observations of the bulk response alone. However, it may be possible to predict material response by understanding the constituent particle interactions and their arrangements. This possibility is investigated here via experiments with a custom built Interfacial Stress Rheometer and densely packed monolayers of repulsive particles and simulations of granular and atomic scale systems. The bulk rheology (G’, G’’) is measured while simultaneously tracking the positions of up to 50,000 particles. We quantify particle microstructure using excess entropy. Results reveal a direct relation between excess entropy and energy dissipation, that is insensitive to the nature of interactions among particles. We use this relation to build a physically-informed model that connects rheology to microstructure. Our findings suggest a framework for tailoring the rheological response of disordered materials by tuning microstructural properties. |
Friday, March 18, 2022 10:00AM - 10:12AM |
Y25.00011: Colloidal suspensions near the fluid phase interface of coupled Lattice-Boltzmann and molecular-dynamics simulations Daniel Cresta, Colin Denniston Lattice-Boltzmann (LB) simulations have been used extensively over the past several decades in the study of hydrodynamics. With computational power increasing, LB methods have been coupled with various molecular dynamics (MD) methods to better simulate complex fluids, phase transitions, and their behaviour at interfaces. Using a modified LB package from the Large-Scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), we couple colloidal particles and the LB fluid mesh under critical conditions to investigate particle dynamics at and near the liquid-gas interface due to variable wetting potentials. This work is preliminary to studying interfacial behaviour of complex fluid suspensions in LAMMPS, such as that of a liquid crystal (LC) colloid suspension, where distinct defect patterns are known to emerge at the LC-gas interface at equilibrium. We expect these defects to disturb the uniformity of the colloidal suspension. |
Friday, March 18, 2022 10:12AM - 10:24AM |
Y25.00012: Intersection of percolation, phase separation and glassy arrest sets minimal conditions for gelation of colloidal systems Scott M Fenton, Brian Ryu, Poornima Padmanabhan, Matthew E Helgeson, Roseanna N Zia Colloidal gelation is an important phenomenon in the formation of colloidal solids. Although separate mechanisms of colloidal gelation (percolation, arrested phase separation, attractive glass formation) have been well established for attractive colloidal systems, how these different mechanisms interact for a particular system is understudied. Specifically, when different mechanisms predict different thresholds for gelation, it is unclear what determines the minimal conditions for gelation. To resolve this ambiguity, we present a new method to precisely establish locations of arrested states in a colloidal phase diagram that uses modulated quenches in attraction strength to determine the gelation threshold for thermoresponsive systems. We identify three distinct regimes of the gelation threshold, which are shared between all in vitro and in silico systems. A detailed investigation of structural and rheological properties in each regime reveals how percolation, phase separation, and glass transition interact to set the gelation threshold. The gelation threshold can be scaled to collapse the gelation behavior of the systems studied suggesting that this behavior is relevant to a wide range of colloidal systems. |
Friday, March 18, 2022 10:24AM - 10:36AM |
Y25.00013: Simulation and Mathematical Modeling of Deposition Regimes in Disordered Packings of Beads Narges Kelly, Thomas Fai, Sujit S Datta, Navid Bizmark Improving filtration efficiencies and lifetime of filters relies on an accurate prediction of the progress of clogging in porous media. More specifically, we try to explain how fluid properties, such as the pressure gradient, and network structure affect the progress of clogging of colloidal particles in microfluidic systems of disordered glass beads. Experiments have shown that depending on the pressure gradient across such systems, we may expect either localized deposition (at lower pressure) or extended deposition (at higher pressure). We try to develop a mathematical model and use agent-based simulations to reproduce the results previously observed during experiments. To do so, we seek to answer what erosion and deposition laws lead to these two different behaviors and whether we can prove the existence of a phase transition theoretically. |
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