Rheological response of entangled isotactic polypropylene melts in strong shear flows: Edge fracture, flow curves, and normal stresses

2021 ◽  
Vol 65 (4) ◽  
pp. 605-616
Author(s):  
Daniele Parisi ◽  
Aijie Han ◽  
Jiho Seo ◽  
Ralph H. Colby
Keyword(s):  
Isotactic Polypropylene ◽  
Shear Flows ◽  
Fracture Flow ◽  
Normal Stresses ◽  
Flow Curves ◽  
Edge Fracture ◽  
Rheological Response ◽  
Strong Shear

Strong shear flows release gaseous nuclei from surface micro- and nanobubbles

2021 ◽  
Vol 6 (4) ◽  
Author(s):  
Zibo Ren ◽  
Shuhong Liu ◽  
Beng Hau Tan ◽  
Fabian Denner ◽  
Fabien Evrard ◽  
...  
Keyword(s):  
Shear Flows ◽  
Strong Shear

scholarly journals Orientational arrest in dense suspensions of elliptical particles under oscillatory shear flows

2021 ◽  
Author(s):  
Zakiyeh Yousefian ◽  
Martin Trulsson
Keyword(s):  
Aspect Ratio ◽  
Shear Flows ◽  
Oscillatory Shear ◽  
Large Strains ◽  
Nematic Order ◽  
Rheological Response ◽  
Lower Viscosity ◽  
Dense Suspensions ◽  
Elliptical Particles ◽  
Shear Jamming

Abstract We study the rheological response of dense suspensions of elliptical particles, with an aspect ratio equal to 3, under oscillatory shear flows and imposed pressure by numerical simulations. Like for the isotropic particles, we find that the oscillatory shear flows respect the Cox-Merz rule at large oscillatory strains but differ at low strains, with a lower viscosity than the steady shear and higher shear jamming packing fractions. However, unlike the isotropic cases (i.e., discs and spheres), frictionless ellipses get dynamically arrested in their initial orientational configuration at small oscillatory strains. We illustrate this by starting at two different configurations with different nematic order parameters and the average orientation of the particles. Surprisingly, the overall orientation in the frictionless case is uncoupled to the rheological response close to jamming, and the rheology is only controlled by the average number of contacts and the oscillatory strain. Having larger oscillatory strains or adding friction does, however, help the system escape these orientational arrested states, which are evolving to a disordered state independent of the initial configuration at low strains and ordered ones at large strains.

scholarly journals Coupling between reconnection and Kelvin-Helmholtz instabilities in collisionless plasmas

2009 ◽  
Vol 16 (2) ◽  
pp. 241-249 ◽  
Author(s):  
D. Grasso ◽  
D. Borgogno ◽  
F. Pegoraro ◽  
E. Tassi
Keyword(s):  
Current Density ◽  
Shear Flows ◽  
Field Model ◽  
Collisionless Plasma ◽  
Three Dimensional ◽  
Dynamical Evolution ◽  
Turbulent Regime ◽  
Helmholtz Instability ◽  
Collisionless Plasmas ◽  
Strong Shear

Abstract. In a collisionless plasma, when reconnection instability takes place, strong shear flows may develop. Under appropriate conditions these shear flows become unstable to the Kelvin-Helmholtz instability. Here, we investigate the coupling between these instabilities in the framework of a four-field model. Firstly, we recover the known results in the low β limit, β being the ratio between the plasma and the magnetic pressure. We concentrate our attention on the dynamical evolution of the current density and vorticity sheets which evolve coupled together according to a laminar or a turbulent regime. A three-dimensional extension in this limit is also discussed. Secondly, we consider finite values of the β parameter, allowing for compression of the magnetic and velocity fields along the ignorable direction. We find that the current density and vorticity sheets now evolve separately. The Kelvin-Helmholtz instability involves only the vorticity field, which ends up in a turbulent regime, while the current density maintains a laminar structure.

Rheological response in shear flows of a thermosensitive elastic liquid in the presence of some additives

2020 ◽  
Vol 59 (5) ◽  
pp. 307-316
Author(s):  
Igor Dal Osto Pereira ◽  
Francisco Ricardo Cunha
Keyword(s):  
Shear Flows ◽  
Elastic Liquid ◽  
Rheological Response

Deformation of grafted polymer layers in strong shear flows

1996 ◽  
Vol 53 (4) ◽  
pp. 3782-3787 ◽  
Author(s):  
J. L. Harden ◽  
M. E. Cates
Keyword(s):  
Shear Flows ◽  
Polymer Layers ◽  
Grafted Polymer ◽  
Strong Shear
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