Magnetic field induced ferrofluid droplet breakup in a simple shear flow at a low Reynolds number

2019 ◽  
Vol 31 (12) ◽  
pp. 127104 ◽  
Author(s):  
Md Rifat Hassan
Keyword(s):  
Magnetic Field ◽  
Reynolds Number ◽  
Shear Flow ◽  
Simple Shear ◽  
Low Reynolds Number ◽  
Droplet Breakup ◽  
Simple Shear Flow ◽  
Low Reynolds

Rigid ring-shaped particles that align in simple shear flow

2013 ◽  
Vol 722 ◽  
pp. 121-158 ◽  
Author(s):  
Vikram Singh ◽  
Donald L. Koch ◽  
Abraham D. Stroock
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Shear Flow ◽  
Simple Shear ◽  
Low Reynolds Number ◽  
Simple Shear Flow ◽  
Rigid Ring ◽  
Axis Of Symmetry ◽  
Low Reynolds ◽  
Axes Of Symmetry

AbstractMost rigid, torque-free, low-Reynolds-number, axisymmetric particles undergo a time-periodic tumbling motion in a simple shear flow, with their axes of symmetry following a set of closed Jeffery orbits. We have identified a class of rigid, ring-like particles whose axes of symmetry instead reach a permanent alignment near the velocity gradient direction with the plane of the particle aligning near the flow–vorticity plane. An asymptotic analysis for small particle aspect ratio (ratio of length parallel to the axis of symmetry to diameter perpendicular to the axis) shows that an appropriate asymmetry of the ring cross-section with a thinner outer edge and thicker inner edge leads to a tendency to rotate in a direction opposite to the vorticity; this tendency can balance the usual rotation rate associated with the finite thickness of the particle. Boundary integral computations for finite particle aspect ratios are used to determine the conditions of aspect ratio and degree of asymmetry that lead to the aligning behaviour and the final orientation of the axis of symmetry of the aligned particles. The aligning particle follows an equation of motion similar to the Leslie–Erickson equation for the director of a small-molecule nematic liquid crystal. However, whereas the alignment of the director arises from intermolecular interactions, the ring-like particle aligns solely due to its intrinsic rotational motion in a low-Reynolds-number flow.

Orientational Distributions of a Ferromagnetic Spherocylinder Particle in a Simple Shear Flow

2002 ◽  
Author(s):  
Masayuki Aoshima ◽  
Akira Satoh ◽  
Geoff N. Coverdale ◽  
Roy W. Chantrell
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Shear Flow ◽  
Flow Field ◽  
Simple Shear ◽  
Applied Magnetic Field ◽  
Spherical Particles ◽  
Simple Shear Flow ◽  
Microstructure Formation ◽  
Base Liquid

A ferrofluid is a suspension of ferromagnetic spherical particles in a base liquid (1), and is well known as a functional fluid which responds to an external magnetic field to give a large increase in the viscosity. Such a significant increase in the viscosity is due to the fact that chain-like clusters are formed owing to magnetostatic interactions between particles in an applied magnetic field. The microstructure formation offers a large resistance to a flow field that gives rise to a significant increase of the apparent viscosity (2).

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