scholarly journals Apparent slip mechanism between two spheres based on solvent rheology: Theory and implication for the shear thinning of non-Brownian suspensions

2018 ◽  
Vol 3 (12) ◽  
Author(s):  
A. Vázquez-Quesada ◽  
Pep Español ◽  
M. Ellero
Keyword(s):  
Shear Thinning ◽  
Slip Mechanism ◽  
Apparent Slip

scholarly journals Simulation of slot-coating of nanocellulosic material subject to a wall-stress dependent slip-velocity at die-walls

2021 ◽  
Author(s):  
P. A. Fuaad ◽  
Agne Swerin ◽  
Fredrik Lundell ◽  
Martti Toivakka
Keyword(s):  
Boundary Layer ◽  
Food Packaging ◽  
Wall Stress ◽  
Barrier Properties ◽  
Shear Thinning ◽  
Two Phase ◽  
Flow Equations ◽  
Slot Coating ◽  
Apparent Slip ◽  
Stress Dependent

AbstractBio-based nanocellulosic materials are non-toxic, renewable, exhibit excellent barrier properties, and are suitable candidates for sustainable food packaging applications. Sizing and designing coating parameters for slot-coating process using nanocellulose suspensions is challenging due to complex shear-thinning rheology and the presence of a water-rich boundary layer, effecting significant apparent slip at the wall. Previous studies have shown that the flow inside the coating bead can be complex, with occasional stagnation regions and a rheological model incorporating yield stress which should be considered while analyzing slot coating of nanocellulosic flows. This work extends earlier investigations by including the effects of the particle depleted water-rich boundary layer. The suspension is modeled as a Casson fluid with a shear-thinning viscosity, and the particle depletion at the wall is represented by an infinitely thin layer modeled as a local shear-dependent nonlinear slip law. The resulting two-phase flow equations are solved using a Finite Volume Method (FVM) coupled with the Volume of Fluid (VoF) method for tracking the free surface interface. It is observed that slip alters the flow’s dynamics in the coating bead, and the effect of slip cannot be ignored, especially at high shear rates. For thin films, the presence of slip enhances the flow, leading to more material coated on the substrate. In contrast, for thicker coatings, apparent slip leads to an augmentation in stagnant, non-yielded regions, potentially generating uneven surfaces.

Study on Wall Slip in Pipeline Flow of Dense Paste

2014 ◽  
Vol 511-512 ◽  
pp. 50-54
Author(s):  
Fu Yan Lv ◽  
Zheng Meng Xia ◽  
Jie Gao ◽  
Xue Di Hao ◽  
Miao Wu
Keyword(s):  
Slip Velocity ◽  
Particle Concentration ◽  
Wall Slip ◽  
Test System ◽  
Pipe Diameter ◽  
Coal Slurry ◽  
Slip Mechanism ◽  
Apparent Slip ◽  
Slip Layer

The apparent wall slip flows of incompressible and viscoplastic fluids in plane pipeline were analyzed assuming that the apparent slip layer consists solely wall slip layershear layerslug flow part and they are independent of the flow rate. Taking coal slurry for example,the experiment is conducted on pressure pipe rheological and resistance characteristic test system. It studies how two key factors (the particle concentration and the pipe diameter) influence the dense paste wall slip velocity. The assumed apparent slip mechanism provides methodologies for the determination of the slip velocity values that are consistent with the traditional Mooney method and furthermore allows the determination of the true shear rate of the dense paste at the wall and the yield stress. The analysis of the slip data of various dense pastes of rigid particles reveals that the apparent slip layer thickness is related to the particle concentration and the pipe diameter.

scholarly journals Air bubbles play a role in shear thinning of non-colloidal suspensions

2021 ◽  
Vol 33 (1) ◽  
pp. 011702
Author(s):  
Yuan Lin ◽  
Ying Wang ◽  
Zixin Weng ◽  
Dingyi Pan ◽  
Jiawang Chen
Keyword(s):  
Colloidal Suspensions ◽  
Shear Thinning ◽  
Air Bubbles
Sign in / Sign up

Export Citation Format

Share Document