Viscosity of Fluids

Question 1

Dynamic viscosity (n)

Answer 1

A measure of a fluid’s resistance to flow. The thicker the fluid, the higher its viscosity. So, honey has a higher dynamic viscosity than water.
n=tau/velocity gradient
n= Ns/m^2 or Pa.s or kg/ms

Question 2

Kinematic viscosity (v)

Answer 2

How easily a fluid flows under the influence of gravity.Water has higher v than oil.
v=n/p
v=m^2/s

Question 3

Newtonian fluids

Answer 3

Behave in a consistent way when you apply force to them as their dynamic viscosity remains constant.
Complies with dynamic viscosity formula.
Not dependent of velocity gradient.

Question 4

Non newtonian fluids

Answer 4

Opposite Newtonian fluids.
Includes time dependent and time independent fluids.

Question 5

Time independent forces

Answer 5

Have a viscosity that does not vary with time.
Pseudoplastic
Dilatant
Bingham/plug flow

Question 6

Time dependent fluids

Answer 6

Viscosity varies with time as well as with velocity
gradient and temperature
Thixotropic fluids
Rheopectic fluids

Question 7

Viscosity index (VI)

Answer 7

Measure of how greatly viscosity changes with
temperature.
A fluid with a high VI exhibits a small change in viscosity with temperature. A fluid with a Low VI exhibits a large change in viscosity with temperature.

Question 8

Rotating drum viscometer

Answer 8

n=tau/velocity gradient
measures high viscosity fluids

Question 9

Capillary tube viscometer

Answer 9

n=(P2-P2)d^2/ 32vL
Newtonian fluids

Question 10

Std calibrated glass capillary viscometer

Answer 10

v=(time)(calibration constant)

Question 11

Falling ball viscometer

Answer 11

n=(ys-yf)d^2/18v
transparent newtonian fluids

Question 12

Saubolt Universal Viscometer

Answer 12

1) @100 degrees fahrenheit and v<75mm^2 use table

2)@100 degrees fahrenheit but v>75mm^2 use:
SUS=4.632v

3) Not 100 degrees fahrenheit:
SUS= A(4.632v)
A=(6.061)(10^-5)t +0.994