Reynolds Experiment and Viscus Flow of Fluids on different surfaces and their flow behavior. Viscosity is the Governing property of Fluids.

1. Abdul Sattar Shar
20CH
Dciplane Chemical Engineering
Fluid Mechanics
Mehran University of Engineering and Technology Jamshoro
Topic Viscus Flow of Fluids

2. Viscous Flow and Its Examples
Contents:
• Reynolds Experiment
• Reynolds Number
• Viscous Fluid Flow
• Behaviour of Viscous flow in a Pipe
• Examples of Viscous FLuids
• conclusion

3. Reynolds Experiment
✧ In early 1883, Reynolds performed his classic
experiment on fluid flow, investigating different flow
rates of water by squirting a jet of dyed water into
water flowing through a large glass pipe. There was a
control valve at one end of the pipe to allow him to
control the velocity.

6. Reynolds Number
✧ The Reynolds number is the ratio of inertial forces to
viscous forces within a fluid.
✧ Reynolds Number = Inertial Force / Viscous Force.
✧ Inertial Force: A force opposite in direction to an
accelerating force acting on a body and equal to the
product of the accelerating force and the mass of the body.
✧ Viscous Force: The force that opposes relative motion
between the layers.

8. Viscous Fluid Flow
✧ ViscousFluid: Viscosity is the property of fluid which offers
resistance to the movement of fluid.
✧ All the real fluids have certain amount of viscosity.
✧ While the visous fluild has a large amount of viscosity.
✧ Examples:
- Honey,
- Molasses
- Glues
- katchup

9. • The flow in which frictional effects are dominent is called viscous flow.

10. ✧ Fluid flows in the form of layers.
✧ The layer which sticks with the wall has the minimum velocity
(aproximately equals to zero) which is called No Slip Condition.
✧ It developes frictional effect at the wall.
✧ Frictional effects are also present between two layers of fluid
and slower layer tries to slow down the faster layer which can
be measured by using viscosity.
✧ Viscous flow is the fluid flow in which the effect of viscosity is
significant.

11. ✧ For example;
- Flow near the boundary walls where the effect of viscosity is
maximum.
- Effects of viscosity is maximum near the boundary so laminar sub-
layer exist near the bounday.

14. Examples
✧ Therefore, moreviscousliquidshavelower rateof flowbecause
viscosity is governing property of fluids.
✧ following aresomeexamplesof viscousfluids:
- Honey
- Engine oil
- Lubricant
- Liquid soap
- Glue
- Printing ink
- etc...

15. conclusion
✧ A fluid with large viscosity resists motion because its strong
intermolecular forces give it a lot of internal friction, resisting the
movement of layers past one another. On the contrary, a fluid
with low viscosity flows easily because its molecular makeup
results in very little friction when it is in motion.
✧ The viscosity of the material is affected by temperature,pressure,
nature of fluid and velocity Gradient etc...

17. THANK YOU