scholarly journals Validation of Fiber Breakage in Simple Shear Flow with Direct Fiber Simulation

2020 ◽  
Vol 4 (3) ◽  
pp. 134
Author(s):  
Tzu-Chuan Chang ◽  
Abrahán Bechara Senior ◽  
Hakan Celik ◽  
Dave Brands ◽  
Angel Yanev ◽  
...  
Keyword(s):  
Shear Flow ◽  
Simple Shear ◽  
Average Length ◽  
Glass Fibers ◽  
Simple Shear Flow ◽  
Fiber Breakage ◽  
Particle Level ◽  
Couette Rheometer ◽  
A Chain ◽  
Length Reduction

This study aims to use particle level simulation to simulate the breakage behavior of glass fibers subjected to simple shear flow. Each fiber is represented as a chain of rods that experience hydrodynamic, interaction, and elastic effects. In order to validate the approach of the model, the simulation results were compared to simple shear flow experiments conducted in a Couette Rheometer. The excluded volume force constants and critical fiber breakage curvature were tuned in the simulation to gain a better understanding of the system. Relaxation of the fiber clusters and a failure probability theory were introduced into the model to solve the fiber entanglement and thus, better fit the experimental behavior. The model showed agreement with the prediction on fiber length reduction in both number average length and weight average length. In addition, the simulation had a similar trend of breakage distribution compared to a loop test using glass fibers.

scholarly journals Experimental Validation of a Direct Fiber Model for Orientation Prediction

2020 ◽  
Vol 4 (2) ◽  
pp. 59
Author(s):  
Sara Andrea Simon ◽  
Abrahán Bechara Senior ◽  
Tim Osswald
Keyword(s):  
Shear Flow ◽  
Shear Strain ◽  
Simple Shear ◽  
Fiber Orientation ◽  
Initial Conditions ◽  
Simple Shear Flow ◽  
Boundary Cell ◽  
Particle Level ◽  
A Chain ◽  
Sliding Plate

Predicting the fiber orientation of reinforced molded components is required to improve their performance and safety. Continuum-based models for fiber orientation are computationally very efficient; however, they lack in a linked theory between fiber attrition, fiber–matrix separation and fiber alignment. This work, therefore, employs a particle level simulation which was used to simulate the fiber orientation evolution within a sliding plate rheometer. In the model, each fiber is accounted for and represented as a chain of linked rigid segments. Fibers experience hydrodynamic forces, elastic forces, and interaction forces. To validate this fundamental modeling approach, injection and compression molded reinforced polypropylene samples were subjected to a simple shear flow using a sliding plate rheometer. Microcomputed tomography was used to measure the orientation tensor up to 60 shear strain units. The fully characterized microstructure at zero shear strain was used to reproduce the initial conditions in the particle level simulation. Fibers were placed in a periodic boundary cell, and an idealized simple shear flow field was applied. The model showed a faster orientation evolution at the start of the shearing process. However, agreement with the steady-state aligned orientation for compression molded samples was found.

scholarly journals Dynamics of a Pair of Paramagnetic Janus Particles under a Uniform Magnetic Field and Simple Shear Flow

2021 ◽  
Vol 7 (1) ◽  
pp. 16
Author(s):  
Christopher Sobecki ◽  
Jie Zhang ◽  
Cheng Wang
Keyword(s):  
Magnetic Field ◽  
Magnetic Material ◽  
Shear Flow ◽  
Simple Shear ◽  
Uniform Magnetic Field ◽  
Particle Orientation ◽  
Viscous Force ◽  
Simple Shear Flow ◽  
A Chain ◽  
The Right

We numerically investigate the dynamics of a pair of circular Janus microparticles immersed in a Newtonian fluid under a simple shear flow and a uniform magnetic field by direct numerical simulation. Using the COMSOL software, we applied the finite element method, based on an arbitrary Lagrangian-Eulerian approach, and analyzed the dynamics of two anisotropic particles (i.e., one-half is paramagnetic, and the other is non-magnetic) due to the center-to-center distance, magnetic field strength, initial particle orientation, and configuration. This article considers two configurations: the LR-configuration (magnetic material is on the left side of the first particle and on the right side of the second particle) and the RL-configuration (magnetic material is on the right side of the first particle and on the left side of the second particle). For both configurations, a critical orientation determines if the particles either attract (below the critical) or repel (above the critical) under a uniform magnetic field. How well the particles form a chain depends on the comparison between the viscous and magnetic forces. For long particle distances, the viscous force separates the particles, and the magnetic force causes them to repel as the particle orientation increases above the configuration’s critical value. As the initial distance decreases, a chain formation is possible at a steady orientation, but is more feasible for the RL-configuration than the LR-configuration under the same circumstances.

Emulsification of particle loaded drops in simple shear flow

2015 ◽  
Vol 470 ◽  
pp. 179-187 ◽  
Author(s):  
Tobias Merkel ◽  
Julius Henne ◽  
Lena Hecht ◽  
Volker Gräf ◽  
Elke Walz ◽  
...  
Keyword(s):  
Shear Flow ◽  
Simple Shear ◽  
Simple Shear Flow

scholarly journals Do Protein Molecules Unfold in a Simple Shear Flow?

2006 ◽  
Vol 91 (9) ◽  
pp. 3415-3424 ◽  
Author(s):  
Juan Jaspe ◽  
Stephen J. Hagen
Keyword(s):  
Shear Flow ◽  
Simple Shear ◽  
Simple Shear Flow ◽  
Protein Molecules

Numerical study of electric field effects on the deformation of two-dimensional liquid drops in simple shear flow at arbitrary Reynolds number

2009 ◽  
Vol 626 ◽  
pp. 367-393 ◽  
Author(s):  
STEFAN MÄHLMANN ◽  
DEMETRIOS T. PAPAGEORGIOU
Keyword(s):  
Steady State ◽  
Shear Flow ◽  
Electric Field ◽  
Electric Fields ◽  
Simple Shear ◽  
Simple Shear Flow ◽  
Physical Parameters ◽  
Shear Stresses ◽  
Two Dimensional ◽  
Liquid Drops

The effect of an electric field on a periodic array of two-dimensional liquid drops suspended in simple shear flow is studied numerically. The shear is produced by moving the parallel walls of the channel containing the fluids at equal speeds but in opposite directions and an electric field is generated by imposing a constant voltage difference across the channel walls. The level set method is adapted to electrohydrodynamics problems that include a background flow in order to compute the effects of permittivity and conductivity differences between the two phases on the dynamics and drop configurations. The electric field introduces additional interfacial stresses at the drop interface and we perform extensive computations to assess the combined effects of electric fields, surface tension and inertia. Our computations for perfect dielectric systems indicate that the electric field increases the drop deformation to generate elongated drops at steady state, and at the same time alters the drop orientation by increasing alignment with the vertical, which is the direction of the underlying electric field. These phenomena are observed for a range of values of Reynolds and capillary numbers. Computations using the leaky dielectric model also indicate that for certain combinations of electric properties the drop can undergo enhanced alignment with the vertical or the horizontal, as compared to perfect dielectric systems. For cases of enhanced elongation and alignment with the vertical, the flow positions the droplets closer to the channel walls where they cause larger wall shear stresses. We also establish that a sufficiently strong electric field can be used to destabilize the flow in the sense that steady-state droplets that can exist in its absence for a set of physical parameters, become increasingly and indefinitely elongated until additional mechanisms can lead to rupture. It is suggested that electric fields can be used to enhance such phenomena.

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