This presentation is about Magnetorheological fluid, its properties and its applications.

1. AM2530: Foundations of Fluid Mechanics
Praveen Zalaya & Mohammed Iqbal,
131501023 & 131501019
Department of Mechanical Engineering
Indian Institute of Technology Palakkad

2. AM2530: Foundations of Fluid Mechanics
Importance of the project topic
Smart fluid whose apparent viscosity can be changed by
varying magnetic field.
Magnetic field polarize and align magnetic particles chain
formation limits particle movement which in turn limits the
movement of the fluid.
Dynamic properties of the fluid can be controlled.
Yield stress of the fluid in active state can be controlled very
accurately by varying magnetic field intensity.
Controlling small millimetre-Oder movements but involving large
force.
https://www.youtube.com/watch?v=KK_h3-BucR0
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3. AM2530: Foundations of Fluid Mechanics
Key terms / definitions
Valve Flow: Fluid is made to flow between static plates by pressure drop
with magnetic field flowing perpendicular to the direction of motion.
Shear Mode: The MR fluid is located between surfaces moving in
relation to each other with magnetic field flowing perpendicular to the
direction of motion of these shear surfaces
Squeeze Flow Mode: The distance between the parallel pole plates
changes with magnetic field flowing perpendicular to the direction of
motion.
Bingham's Equation τ = τy (H) + η dv/dz τ≥ τy
τ = G Ɣ , τ< τy
web.iitd.ac.in/~hirani/MR%20fluids.pdf .

4. AM2530: Foundations of Fluid Mechanics
Description of fluid flow
2-D
Laminar
Viscous
Fully developed
Steady flow
http://www.sae.org/automag/techbriefs/10-2001/03.gif
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5. AM2530: Foundations of Fluid Mechanics
Description of fluid.
Polarization(magnetic particle property)
Permeability degree of
magnetization of a material that
responds linearly to an applied
magnetic field.
web.iitd.ac.in/~hirani/MR%20fluids.pdf
.

6. AM2530: Foundations of Fluid Mechanics
Related problems / solutions discussed in class
or textbooks
Poisuelle flow. Consider fluid in a pipe of
circular cross-section (pipe radius R). One end of the pipe
is at higher pressure, from where the fluid enters, when
compared to the other end of the pipe, from where the
fluid exits. The viscosity of fluid is µ and the density is ρ
Vz = −(P′R^2/ 4µ) (1− r^2/ R^2)
˚ γrz =˚ γzr =P′r /2µ , τrz = τzr =P′r/ 2
Where P is combined effect prezsure and gravity
.
Couette flow Consider fluid between two
parallel plates (plate separation h), with one of
plates being stationary while the other moving with
a velocity V0. The viscosity of fluid is µ and the
density is ρ.
Vx = Voy/ h
˚ γxy =V0/ h (rate of shear strain)
τxy = µVo/ h (shear stress)
http://math.ubooks.pub/Books/M1/1703/MAIN/images/Figure_12_04_05a.jpg
https://cgi.tu-harburg.de/~ttwww/img/couette_beschr.jpg
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7. AM2530: Foundations of Fluid Mechanics
Related problems / solutions discussed in class
or textbooks (contd.)
Squeeze flow: A circular plate of
1m diameter is pushed towards
another stationary circular plate
below it at a velocity vp which may
vary with time.
v= vp(t)D/4h
http://book.transtutors.com/qimage/image10092014530.png
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8. AM2530: Foundations of Fluid Mechanics
• Sedimentation: MR fluid Consist micron (1-
10 μm) sized, magnetically polarizable (soft
magnets) dispersed in a carrier liquid such
as mineral, silicone oils, kerosene, water.
ƒParticles > 10 μm~ unstable against settling
( )
η
ρρ
9
2
velocitysettlingsStoke'
2
P if ga−
=
• Challenges: Systematic material science oriented studies
concerning MR fluid are still lacking.
From an engineering viewpoint
the durability of MR fluids and that of device
has been - and remains - a major challenge.
There are no systematic published studies of
Factors affecting the durability of MR fluids and devices.
• Precaution: Ensure that the lines of flux are perpendicular
to the direction of the motion to be restricted.
20-50% by vol. Magnetic particles
(higher vol. Increase “off state” viscosity).
https://upload.wikimedia.org/wikipedia/commons/a/a3/Mr_fluid_squeezeflowmode.jpg
web.iitd.ac.in/~hirani/MR%20fluids.pdf
web.iitd.ac.in/~hirani/MR%20fluids.pdf .

9. AM2530: Foundations of Fluid Mechanics
Application
Most devices that use MR fluids can be classified as having:
– Fixed poles (Pressure driven flow mode)
Servo-valves, dampers and shock absorbers
– Relatively moveable poles (Direct-shear/sliding mode).
• Clutches, brakes, chucking and locking devices.
Motion damping is perhaps the most
practical use for MR technology today
web.iitd.ac.in/~hirani/MR%20fluids.pdf
.

10. AM2530: Foundations of Fluid Mechanics
Summary
• Three modes – Valve flow ( poisuelle flow), shear flow(couette
flow), squeeze flow.
• MR fluid has ability to transmit force can be controlled with an
electromagnet which gives rise to its many possible control-
based applications.
• The characteristic of shear stress versus strain rate can be
controlled by the applied magnetic field.
• MR fluid has a lot of application in damping, brakes, engine
mount and valves.
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