Bulletin of the American Physical Society
75th Annual Meeting of the Division of Fluid Dynamics
Volume 67, Number 19
Sunday–Tuesday, November 20–22, 2022; Indiana Convention Center, Indianapolis, Indiana.
Session J19: Non-Newtonian Flows: Rheology |
Hide Abstracts |
Chair: Rishabh More, MIT; Sumit Tripathi, Institute of Infrastructure, India Room: 205 |
Sunday, November 20, 2022 4:35PM - 4:48PM |
J19.00001: Rheological characterization and modeling studies of highly concentrated emulsions Sumit Tripathi Highly concentrated emulsions (HCEs) are high viscosity fluids having complex rheological properties. In this work, rheological properties of water-in-oil HCE, having 93.5% internal phase volume fraction, are characterized using five deformation modes: shear sweep, amplitude sweep, frequency sweep, creep, and relaxation tests. Each test provides significant insights into the complex behavior of HCE resulting from the tight droplet packing, polydispersity, interfacial tension between the two phases and viscosity differences. The rotary rheological tests indicate that the viscosity of HCE is significantly decreased with increase in shear rate, and the HCE typically behaves like a shear-thinning fluid. The oscillatory rheological tests primarily determine the structural stability of the HCE and indicate that at low shear stress values the emulsions behave like an elastic material, and once the shear stress is increased past the yield stress, the viscous effects dominate. The creep and relaxation tests indicate that the HCE is quite stable when the shear stress values are within the yield stress, beyond which it behaves like a viscoelastic material. An attempt is also made to compare the experimental rheological data with theoretical models available in the literature. |
Sunday, November 20, 2022 4:48PM - 5:01PM |
J19.00002: Rheological Properties of Zinc Ferrite Ferrofluid under the Influence of Strain Rate and Applied Magnetic Field Gbadebo T Yusuf, Abideen A Ibiyemi Deformation of the magnetic aggregate and destruction of the field-induced structure are the main issues affecting the rheology of magnetic fluid, and this has had significant negative effects on rheological systems. The percentage of the strain rate determines how much deformation will occur. However, this research focused on the effects of strain rate and magnetic field on the rheological characteristics of zinc ferrite Ferrofluid (FF) using an oscillatory sweep test. Anhydrous iron (III) chloride (FeCl3) and zinc (II) chloride hexahydrate are combined to form the solution needed to synthesize zinc ferrite magnetic nanoparticles (ZnCl2.6H2O). The TEM analysis was conducted and shows the samples with spherically shaped nanoparticles. The XRD analysis revealed a cubic structure with trivalent Fe-phase formation. Tetrahedral site A and octahedral site B have hopping lengths of 3.61 nm and 2.94 nm respectively, while lattice parameters a and c were found at 8.3298 Å and 13.7501 Å respectively. In both the absence and presence of magnetic fields, the rheology of the fluid is studied at strain amplitudes of 1%, 10%, 33%, and 100%. As the strain percentage increases, so did the deformation's degree of distortion. Low deformation is formed at strains of 1 and 10 %, which leads to the development of an improved and better rheological systemic function. At strain 33 %, however, the rheological function partially deteriorates, while the structural deformation improves. The rheological system is significantly weakened when under 100% strain, but was strengthened when under 1% strain. The storage modulus (G′) was generally found to be greater than the loss modulus indicating the formation of the dominant elastic structure. |
Sunday, November 20, 2022 5:01PM - 5:14PM |
J19.00003: The Flow of Wormlike Micellar Gels in Narrow Capillaries Ronak R Gupta, Masoud Daneshi, Gwynn J Elfring, Ian Frigaard Wormlike micellar solutions formed by long-chained zwitterionic surfactants show gel-like rheology at room temperature and have recently been found to exhibit other complex and interesting rheological features. We study the capillary flow of these wormlike micellar gels in a canonical flow scenario using optical coherence tomography-based velocimetry and report the existence of plug flows with strong wall-slip along with non-parabolic velocity profiles with shear-layers for different surfactant concentrations and imposed flowrates. These experiments shed light on the fluid dynamics of wormlike micelles in simple geometries and inform ongoing attempts to understand the cross-talk between the rheology and flow of soft matter. |
Sunday, November 20, 2022 5:14PM - 5:27PM |
J19.00004: Three-dimensional measurement of a flow in a rectangular channel using a photoelastic method Yoshiyuki Tagawa, Nakamine Kento, Yuto Yokoyama, Masakazu Muto The purpose of this study is to measure the shear rate distribution of a flow in a rectangular by using integrated photoelasticity. We measrued a mixed solution of photoelastic material crystals, cellulose nanoctystal (CNC), to elucidate whether there are any phenomena (trends) peculiar to CNC mixed solution that differ from those to the solid case. In addition, we examine the stress-optic for CNC mixed solution using a high-speed polarization camera to measure the retardation and orientation angles of polarized lights. We compare the experimentally measured retardation distribution and the theoretical secondary principal stress difference distribution based on the analytical solution in steady laminar flow. Results show that retardation, which was not caused by stress, appeared in the CNC mixed solution. We compared the secondary principal stress difference distribution with the retardation distribution offsetting the effect of the retardation specific to the CNC mixed solution. The result showed that the spatial intensity distributions of both agreed with a relative error of 3.84%. We conducted additional verification for different flow rates (10, 20 ml/min). As a result the relative errors were 5.67% and 3.24% for flow rates of 10 and 20 ml/min, respectively. |
Sunday, November 20, 2022 5:27PM - 5:40PM |
J19.00005: The fluid dynamics of dripping onto a substrate Gareth H McKinley, Konstantinos Zinelis, Thomas Abadie, Omar K Matar Extensional flows of complex fluids are important in many industrial applications such as spraying and atomisation, and microfluidic-based drop deposition. Dripping-on-Substrate (DoS) is a conceptually-simple, but dynamically-complex, probe of the extensional rheology of low viscosity non-Newtonian fluids. It incorporates the capillary-driven thinning of a liquid bridge, produced by a single drop as it is dispensed from a syringe pump onto a solid substrate. By following the filament thinning process the extensional viscosity and relaxation time of the sample can be determined. Importantly, it allows experimentalists to measure the extensional properties of lower viscosity solutions than is possible with commercially-available capillary break-up extensional rheometers. Understanding the fluid mechanics behind the operation of DoS will allow us to optimise and extend the performance of this protocol. To achieve this we employ a computational rheology approach using adaptively-refined axisymmetric numerical simulations with the open-source Eulerian code, Basilisk. The volume-of-fluid technique is used to capture the moving interface, and the log-conformation transformation provides a stable and accurate solution of the viscoelastic constitutive equation. Here we focus on understanding the role of elasticity and finite chain extensibility on controlling the Elasto-Capillary (EC) regime, as well as the perturbative effects that gravity and the wetting of the solid substrate play in setting the evolution of the self-similar thinning and pinch-off dynamics. To illustrate the interplay of these different forces we construct a simple one-dimensional model that captures the initial rate of thinning, when the interplay of inertia and capillarity dominates and the structure of the transition region to the non-linear EC regime where the rapidly growing elastic stresses in the thread balance the capillary pressure as the filament thins towards breakup. |
Sunday, November 20, 2022 5:40PM - 5:53PM |
J19.00006: Optimal liquid bridges for extensional rheometry Joseph Connell, Murray Rudman, Ranganathan Prabhakar The capillary thinning of liquid bridges is commonly exploited for measuring the extensional viscosity of Newtonian and complex fluids. The viscosity is extracted typically by comparing the prediction of the capillary thinning obtained with a mid-filament stress balance against the radial thinning data experimentally obtained with a test sample. The prediction of the stress balance is expected to be valid only close to pinch-off, and often cannot match the full thinning profile of the mid-filament radius. |
Sunday, November 20, 2022 5:53PM - 6:06PM |
J19.00007: Rheological and flow characteristics of extensible yield stress fluids Mohamed S Abdelgawad, Simon J Haward, Amy Q Shen, Marco E Rosti Many industrial fluids commonly used in 3D printing, food industries, and pharmaceutical applications are yield stress fluids with elastic nature (elastoviscoplastic fluids, EVP). The inherited elasticity of such fluids allows them to store energy, thus, they can partially recover after deformation and resist extension. Elastic effects have been shown to be responsible for phenomena such as the loss of fore-aft symmetry and the formation of a negative wake behind a spherical particle settling in EVP fluids, and the cusped shape of a bubble rising in EVP fluid. In practice, the extensional characteristics of EVP fluids are found to speed up the dispensing process when they are used as inks for 3D printing systems. However, there is a drawback of secondary droplets formation, after the breakup of the liquid filament, which may fall randomly and negatively affects the precision. Hence, tuning the elasticity of EVP materials and studying its effect in different flow scenarios is very important. To achieve a tunable extensional behaviour, we modify a well-studied EVP fluid (Pluronic F127 solution, PF127) by adding a high-polymer (poly ethylene oxide, PEO) at different concentrations. We report the effect of PEO addition on the shear and extensional rheology, as well as the flow behaviour of the modified materials. |
Sunday, November 20, 2022 6:06PM - 6:19PM |
J19.00008: Shear-thinning effect on three-dimensional flow structure of complex fluid in optimized shape cross-slot extensional rheometer (OSCER) Junkyu Kim, Hyoungsoo Kim OSCER can measure the rheological properties of complex fluids at a higher extension rate than capillary breakup extensional rheometer. The shape of OSCER has been numerically optimized for a regular cross-slot under a two-dimensional flow assumption using 'upper-convected Maxwell model', however, which can only consider elastic fluid with constant viscosity. Typically, complex fluids such as polymer melts, polymer solutions, and bio-fluids including blood and DNA solution can have both elastic properties and shear-thinning viscosity simultaneously. Although both properties can affect flow structure within OSCER influencing flow instability and rheological measurement, it has rarely been investigated. In this study, we numerically study the three-dimensional flow structure of complex fluid in OSCER depending on shear-thinning properties. In conclusion, we will discuss the working conditions of OSCER depending on shear-thinning properties of complex fluids. |
Sunday, November 20, 2022 6:19PM - 6:32PM |
J19.00009: Small Amplitude Oscillatory Extensional Rheometry for Viscoelastic Filaments Subramaniam Balakrishna, William W Schultz We revise a method of simultaneously characterizing multiple fluid parameters for a Newtonian filament by extending to viscoelastic filaments. We use oscillatory deformation that avoids breakup and imposes an external timescale. When combined with image processing to determine the free surface at various phases, this procedure can simultaneously determine the dimensionless surface tension, viscosity, relaxation and retardation times. We consider parametric strategies to determine an optimal regime for measurement under conditions of full and limited resolution. |
Sunday, November 20, 2022 6:32PM - 6:45PM |
J19.00010: A New Generalized Reynolds Number Formulation for Pseudo-Plastic Fluids Coskun Bilgi, Niema M Pahlevan Physical variables of a system can be mapped to a set of dimensionless parameters (Buckingham theorem). For a fluid dynamics problem, the Reynolds number is one of the commonly used parameters. The common practice to compare the shear-thinning properties of biofluids may be misguided due the inappropriate use (formulation) of the Reynold number. To address this issue, we propose a new generalized Reynolds number formulation that takes advantage of the measurement principle of rotational viscometers in the Darcy friction relation. This measurement principle relies on Newtonian approximations, that enables our formulation to be independent of the viscosity model. To test our formulation, we design a series of Poiseuille flow experimentations. In addition to these experiments, we compare our model with established generalized Reynolds number formulations. The results of experiments and comparisons with the literature show excellent agreement with our proposed theory. Our formulation can greatly impact both computational and experimental fluid mechanics by matching the groups of various rheology models. This would highlight the true non-Newtonian effects and unearth the unrealistically enhanced differences. |
Sunday, November 20, 2022 6:45PM - 6:58PM |
J19.00011: Viscous fingering enables equipment-free rheometry of complex fluids in resource-constrained settings Sampad Laha, Dr. Aditya Bandopadhyay, Prof. Suman Chakraborty Rheological characterization of complex fluids often holds the key for a wide gamut of analytical applications. However, installation and deployment of sophisticated instruments like rheometer is unpragmatic in case of resource-limited settings. As a simple alternative, we have developed an equipment-free methodology called 'Rheometry-on-paper', in which fluid rheological properties can be accurately predicted by analyzing the viscous fingering patterns of a drop of fluid on a wet paper strip. The fingering instability, also known as the Saffman-Taylor instability, arises as a less viscous fluid tries to displace a more viscous one, such as glycerol, through a porous domain. Through box counting method, the fractal dimension value of the topologically complex interface is determined and mapped with the corresponding rheological indices, thereby enabling rapid rheometrical characterization at ultra-low cost without the help of any sophisticated instrumentation. Using this method, we have been able to accurately measure the rheological parameters of complex Non-Newtonian fluids such as particle suspensions in aqueous polymeric solutions, as well as determine the effect of particle volume fraction and polymer concentration on the overall rheological signature of the fluid. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700