Article
Chemistry, Physical
Vinay Vaibhav, Juergen Horbach, Pinaki Chaudhuri
Summary: Using numerical simulations, this study examines the flow behavior of a model glass-forming binary mixture with large particle size ratio. The research focuses on the rheological response to applied shear in the regime where the larger species dominate spatially. The study shows that as density increases, macroscopic rigidity emerges in the regime where the larger species undergo glass transition while the smaller species remain highly diffusive. The analysis reveals the interplay between shear timescale and quiescent relaxation dynamics of the two species, offering microscopic insights into the observed rheological response. Additionally, by adjusting the composition of the mixture, the study demonstrates that the systematic insertion of smaller particles affects the rheology by reducing system viscosity.
Article
Physics, Fluids & Plasmas
Samya Sen, Anthony G. Morales, Randy H. Ewoldt
Summary: The study reveals that thixotropic aging suppresses drop splashing during impact, leading to the proposal of hypotheses for modifying dimensionless groups. Steady flow properties cannot be defined or measured due to the rejuvenation and breakdown of microstructure caused by deformation.
PHYSICAL REVIEW FLUIDS
(2021)
Article
Physics, Multidisciplinary
Farshad Nazari, Kourosh Shoele, Hadi Mohammadigoushki
Summary: We present a study on the locomotion of a helical swimmer in yield stress fluids, which involves three stages. In the first stage, the swimmer needs to overcome the yield strain of the material to achieve rotational motion. However, surpassing the first threshold alone does not lead to locomotion. Only when the viscous forces are strong enough to cause plastic deformation of the material, resulting in movement away from the swimmer, can net locomotion occur. In the third stage of locomotion, the yield stress affects swimming differently at small and large pitch angles, retarding or enhancing the swimming speed respectively. Flow visualizations demonstrate highly localized flow near the swimmer in yield stress fluids.
PHYSICAL REVIEW LETTERS
(2023)
Article
Polymer Science
Vladimir Shelukhin
Summary: The new mathematical model developed for rotational sedimentation of particles in a concentric-cylinder Couette geometry shows good agreement with known measurement data, validating its accuracy. Sedimentation is proven to occur due to particles' rotation and rotational diffusion according to the proposed theory.
Article
Engineering, Mechanical
Muhammad Mohasan, Anas Bin Aqeel, Pengyu Lv, Yantao Yang, Huiling Duan
Summary: This study numerically investigates the impact of a water droplet onto a deep oil pool, focusing on cavity dynamics and the effects of pool liquid viscosity and impacting velocity. Different regimes with and without splashing are identified, and power-law scalings are proposed to describe the dependencies of cavity depth and time on impact velocity and pool liquid viscosity.
ACTA MECHANICA SINICA
(2021)
Article
Engineering, Manufacturing
A. Geffrault, H. Bessaies-Bey, N. Roussel, P. Coussot
Summary: This study systematically tests the deposition behavior of yield stress fluids under different material and printing parameters, and identifies various deposition patterns. The transitions between pattern regions are predicted through theoretical arguments, and a generic diagram is presented. This is of great importance for optimizing practical processes and designing specific deposition patterns.
ADDITIVE MANUFACTURING
(2023)
Article
Mechanics
A. Geffrault, H. Bessaies-Bey, N. Roussel, P. Coussot
Summary: We investigate different flow regimes of a filament generated through extrusion and propose a simple method to determine the elongational yield stress of simple yield stress fluids. We show that the drop mass after filament breakage and the estimation of the critical radius at the solid-liquid transition can be used to estimate the shear yield stress. Our findings suggest that this approach is valid in a wide range of extrusion velocities and can provide an instantaneous estimation of the shear yield stress without sophisticated equipment.
JOURNAL OF RHEOLOGY
(2023)
Article
Chemistry, Physical
Miguel Balzan, Ayoub Abdollahi, Frederick S. Wells, Geoff R. Willmott
Summary: Experimental study of vertical drop impacts of dairy-based solutions on smooth stainless steel surfaces was conducted using high-speed photography. Results showed that the behavior of different fluids during impact was mainly determined by their rheological properties. The maximum spreading diameter and the time to reach maximum spread were influenced by shear-thinning effects.
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
(2021)
Article
Mechanics
A. Pourzahedi, M. Zare, I. A. Frigaard
Summary: Bubbles rising steadily in Carbopol often have an inverted teardrop shape with a pointed tail, which may be caused by viscoelasticity or fluid memory effects. Even after eliminating all possibilities of memory effects, the pointed tail still exists in steady bubble propagation. This suggests that the tail shape results from a combination of rheology and steady fluid deformation around the rising bubble.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2021)
Article
Mechanics
Rodrigo S. Mitishita, Jordan A. MacKenzie, Gwynn J. Elfring, Ian A. Frigaard
Summary: Research on turbulent flows of high Reynolds number viscoplastic fluids has been conducted, and an experimental study was carried out to investigate the effect of different concentrations of Carbopol on the rheology and turbulence statistics of the fluid.To increase Reynolds number with a Carbopol solution, streamwise Reynolds stresses approach Newtonian values in the core, suggesting diminishing effects of shear-thinning. The addition of Carbopol enhances turbulence anisotropy and alters energy content at different scales in comparison to water.
JOURNAL OF NON-NEWTONIAN FLUID MECHANICS
(2021)
Article
Chemistry, Physical
Mattia Carneri, Davide Ferraro, Afshin Azarpour, Alessio Meggiolaro, Sebastian Cremaschini, Daniele Filippi, Matteo Pierno, Giuliano Zanchetta, Giampaolo Mistura
Summary: The use of highly slippery lubricated surfaces can facilitate the movement of high-viscosity YSF droplets. The droplets slide on the lubricated surfaces and roll down when their descending speed increases, especially at high inclinations and low concentrations.
JOURNAL OF COLLOID AND INTERFACE SCIENCE
(2023)
Article
Instruments & Instrumentation
Olfa D'Angelo, Felix Kuthe, Kasper van Nieuwland, Clint Ederveen Janssen, Thomas Voigtmann, Maziyar Jalaal
Summary: We present a setup for systematic studies on droplet spreading of complex fluids under microgravity conditions. By adjusting the gravitational acceleration, different spreading dynamics regimes can be accessed. The experimental module allows for the deposition of droplets and offers multiple observation and analysis methods under microgravity.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2022)
Article
Polymer Science
Hugo A. Castillo-Sanchez, Leandro F. de Souza, Antonio Castelo
Summary: In this study, complex rheological behavior is described using models implemented in the HiGTree/HiGFlow system. The models are successfully compared with two other methodologies, and the mesh convergence analysis shows the excellent performance of the HiGFlow software. Importantly, the implemented methodology reproduces rheological behavior of high interest in the rheology community.
Article
Chemistry, Physical
M. J. Hayes, M. Smith
Summary: This study explores the effect of aging on the break-up dynamics of Laponite suspensions in an extensional geometry. The results show that aging not only leads to stronger necking at the midpoint of the samples but also increases the stress overshoot with decreasing yield strain. However, the thinning curves in extension are found to be insensitive to the yield strain, suggesting significant plastic deformations in the samples before complete yielding. The implications of these findings for assessing the ductile-brittle nature of samples are also discussed.
EUROPEAN PHYSICAL JOURNAL E
(2022)
Article
Thermodynamics
G. Mishra, P. Mishra, R. P. Chhabra
Summary: This study numerically investigates the laminar free convection in yield-pseudoplastic fluids in concentric and eccentric cylindrical annuli. The findings reveal that the eccentric positioning of the heated cylinder enhances heat transfer, while the horizontal shifting of the inner cylinder to an off-centre position has an adverse effect on heat transfer.
INTERNATIONAL JOURNAL OF THERMAL SCIENCES
(2022)
