Yield stress and wall slip of kaolinite networks

2021 ◽  
Vol 33 (5) ◽  
pp. 053105
Author(s):  
Aref Abbasi Moud ◽  
Jade Poisson ◽  
Zachary M. Hudson ◽  
Savvas G. Hatzikiriakos
Keyword(s):  
Yield Stress ◽  
Wall Slip

The influence of wall slip on yield stress and viscoelastic measurements of cement paste

2001 ◽  
Vol 31 (2) ◽  
pp. 205-212 ◽  
Author(s):  
Aaron W. Saak ◽  
Hamlin M. Jennings ◽  
Surendra P. Shah
Keyword(s):  
Yield Stress ◽  
Cement Paste ◽  
Wall Slip

scholarly journals Viscoplastic Couette Flow in the Presence of Wall Slip with Non-Zero Slip Yield Stress

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3574 ◽  
Author(s):  
Yiolanda Damianou ◽  
Pandelitsa Panaseti ◽  
Georgios C. Georgiou
Keyword(s):  
Shear Stress ◽  
Steady State ◽  
Yield Stress ◽  
Couette Flow ◽  
Wall Slip ◽  
Threshold Value ◽  
Bingham Plastic ◽  
Navier Slip ◽  
Angular Velocities ◽  
Slip Yield Stress

The steady-state Couette flow of a yield-stress material obeying the Bingham-plastic constitutive equation is analyzed assuming that slip occurs when the wall shear stress exceeds a threshold value, the slip (or sliding) yield stress. The case of Navier slip (zero slip yield stress) is studied first in order to facilitate the analysis and the discussion of the results. The different flow regimes that arise depending on the relative values of the yield stress and the slip yield stress are identified and the various critical angular velocities defining those regimes are determined. Analytical solutions for all the regimes are presented and the implications for this important rheometric flow are discussed.

Capillary Flow of Yield-Stress Fluids in Microchannels

2006 ◽  
Author(s):  
V. Bertola
Keyword(s):  
Yield Stress ◽  
Flow Regime ◽  
Capillary Flow ◽  
Capillary Tube ◽  
Plug Flow ◽  
Wall Slip ◽  
Critical Distance ◽  
Tube Diameter ◽  
Force Balance ◽  
Theoretical Argument

The wicking of a model yield-stress fluid (hair-gel solution in water) in a capillary tube is studied experimentally. By changing the hair-gel concentration in the solution, the yield stress varied from 5 to 20 Pa. A simple force balance between capillary and viscous forces suggests that the fluid should stop flowing as soon as the wall shear stress reaches the yield value, at a critical distance from the inlet which is independent of the tube diameter. However, this theoretical argument is not confirmed by experiments, which show that the fluid moves well beyond the critical distance determined theoretically, and that there is a well-defined effect of the tube diameter. It is proposed that such behavior may be determined by wall slip, which causes the flow to switch from the Poiseuille flow regime to the plug flow regime.

Apparent Wall Slip in Capillary Rheometry of Viscoplastic Liquids

2005 ◽  
Author(s):  
Paulo R. Souza Mendes ◽  
Jose´ R. R. Siffert ◽  
Eduardo S. S. Dutra
Keyword(s):  
Shear Stress ◽  
Yield Stress ◽  
Wall Slip ◽  
Momentum Conservation ◽  
Conservation Equation ◽  
Jump Number ◽  
Capillary Rheometry ◽  
Viscosity Function ◽  
Novel Material ◽  
Apparent Wall Slip

We employ a recently proposed viscosity function (Souza Mendes and Dutra, 2004) to analyze the fully developed flow of yield-stress liquids through tubes. We first show that its dimensionless form gives rise to the so-called jump number, a novel material property that measures the shear rate jump that the material undergoes as the yield stress is reached. We integrate numerically the momentum conservation equation that governs this flow together with the generalized Newtonian Liquid model and the above mentioned viscosity function. We obtain velocity and viscosity profiles for the entire range of the jump number. We show that the friction factor f.Re curves display sharp peaks as the shear stress value at the tube wall approaches the yield stress. Finally, we demonstrate the existence of sharp flow rate increases (or apparent slip) as the wall shear stress is increased in the vicinity of the yield stress.

Cessation of Newtonian circular and plane Couette flows with wall slip and non-zero slip yield stress

Meccanica ◽  
2016 ◽  
Vol 52 (9) ◽  
pp. 2081-2099 ◽  
Author(s):  
Maria Philippou ◽  
Yiolanda Damianou ◽  
Xenia Miscouridou ◽  
Georgios C. Georgiou
Keyword(s):  
Yield Stress ◽  
Wall Slip ◽  
Slip Yield Stress

scholarly journals On the origin of start-up effects in ply-ply friction for UD fiber-reinforced thermoplastics in melt

2021 ◽  
Author(s):  
Rens Pierik ◽  
Wouter Grouve ◽  
Sebastiaan Wijskamp ◽  
Remko Akkerman
Keyword(s):  
Shear Stress ◽  
Yield Stress ◽  
Nonlinear Viscoelasticity ◽  
Wall Slip ◽  
Simulation Software ◽  
Design Stage ◽  
Fiber Reinforced ◽  
Press Forming ◽  
Start Up ◽  
Long Time

Hot press forming is an attractive production technology to fulfil the increasing demand for complex fiber-reinforced thermoplastic parts. Over the years, process simulation tools on press forming have shown to be very helpful in facilitating the design stage for defect free parts production. One of the important deformation mechanisms considered in process simulations is the relative slip of successive plies or ply-ply friction, of which the underlying principles need to be better understood in order to improve the overall predictive simulation quality. In particular the use of steady-state friction values, neglecting the transient response, is questionable as experiments showed that shear stress overshoots can be as high as three times the long-time value. The phenomenon of the overshoot at start-up shear is analyzed. Possible explanations include nonlinear viscoelasticity and a slip relaxation effect giving rise to wall slip, which are discussed using relevant ply-ply friction measurements carried out on a dedicated friction test set-up. Experimental results on UD C/PEEK show that the shear stress build up and subsequent relaxation comply with nonlinear viscoelasticity. However, the long-time shear stress fails to match the matrix material’s viscosity, possibly due to a yield stress. The flow curve corrected for a yield stress resembles the effects of wall slip. A transient model according to these findings will enhance the accuracy of press forming simulation software.

Dynamic characteristics of magnetorheological fluid squeeze flow considering wall slip and inertia

2019 ◽  
Vol 31 (2) ◽  
pp. 229-242 ◽  
Author(s):  
Xinjie Zhang ◽  
Ruochen Wu ◽  
Konghui Guo ◽  
Piyong Zu ◽  
Mehdi Ahmadian
Keyword(s):  
Yield Stress ◽  
Excitation Frequency ◽  
Dynamic Environment ◽  
Dynamic Test ◽  
Inertial Force ◽  
Control Valve ◽  
Wall Slip ◽  
Magnetorheological Fluid ◽  
Squeeze Flow ◽  
Vertical Force

Magnetorheological fluid has been investigated intensively nowadays, and magnetorheological fluid shows large force capabilities in squeeze mode with wide application potential such as control valve, engine mounts, and impact dampers. In these applications, magnetorheological fluid is flowing in a dynamic environment due to the transient nature of inputs and system characteristics. Hence, this article undertakes a comprehensive study of magnetorheological fluid squeeze flow dynamics behaviors with wall slip, yield, and inertia. First, the dynamic model with the bi-viscous constitutive of magnetorheological fluid squeeze flow including wall slip and inertial force is presented. Then, the mathematical model is validated, matching magnetorheological fluid squeeze dynamic test results very well. Finally, the dynamics behavior and mechanism of magnetorheological fluid squeeze flow with inertia, yield, and wall slip are explored. Results show that (1) increasing yield stress and decreasing initial gap will increase the magnetorheological fluid vertical force greatly; (2) the wall slip affects the yield surface of magnetorheological fluids in the squeeze zone and affects the squeeze force; (3) the inertial force is increasing tremendously as the increased excitation frequency and yield stress and should be included with high-frequency excitation or yield stress.

scholarly journals Carbomer microgels as model yield-stress fluids

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Zdzisław Jaworski ◽  
Tadeusz Spychaj ◽  
Anna Story ◽  
Grzegorz Story
Keyword(s):  
Yield Stress ◽  
Soft Matter ◽  
Flow Characteristics ◽  
Wall Slip ◽  
Future Research ◽  
Cross Linking ◽  
Model Yield ◽  
Liquid Transition ◽  
Microgel Particles ◽  
2D And 3D

Abstract The review presents current research results for Carbopol-based microgels as yield-stress materials, covering three aspects: chemical, physical and rheological. Such a joint three-aspect study has no analog in the literature. The chemical aspects of Carbopol polymers are presented in terms of a cross-linking polymerization of acrylic acid, their molecular structure, microgel formulation, polyacid dissociation and neutralization, osmotic pressure and associated immense microgel swelling. The physical characterization is focused on models of the shear-induced solid-to-liquid transition of microgels, which are formed of mesoscopic particles typical for soft matter materials. Models that describe interparticle effects are presented to explain the energy states of microgel particles at the mesoscale of scrutiny. Typical representatives of the models utilize attributes of jamming dispersions, micromechanical and polyelectrolyte reactions. Selected relationships that result from the models, such as scaling rules and nondimensional flow characteristics are also presented. The rheological part presents the discussion of problems of yield stress in 2D and 3D deformations, appearance and magnitude of the wall slip. The theory and characteristics of Carbopol microgel deformation in rotational rheometers are presented with graphs for the steady-state measurements, stress-controlled oscillation and two types of transient shear deformation. The review is concluded with suggestions for future research.

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