Hot on the trail of the Very Viscous Liquid!

Maria Ekiel – JeżewskaMaciej Lisicki

What is viscosity?

What features characterize the motion of the Very Viscous Liquid?

Let's experiment!

In which liquid is it harder to manipulate a spoon? Which exerts larger drag on the spoon?

1. Mixing of tea and mixing of honey

THIS ONE!

Very Viscous Liquid

In which liquid is it harder to move a spoon? Which exerts larger drag on the spoon?

1. Mixing of tea and mixing of honey

In which liquid it it easier to make it move? Which one could be honey?

2. Making liquids move

G.M. Homsy, Multimedia Fluid Mechanics, Cambridge Univ. Press

THIS ONE!

Very Viscous Liquid6G.M. Homsy, Multimedia Fluid Mechanics, Cambridge Univ.

Press

In which liquid it it easier to make it move? Which one could be honey?

2. Making liquids move

– I can't keep pace with you! – shouted the liquid from inside a glass, which has just started rotating.

Was this the voice of tea or honey?

3. The spinning glass

After an hour the rotation stopped. Did the tea or honey still move afterwards?

3. The spinning glass

4. The mystery of floating radish

A puzzle:We will show you two liquids: A and B.Which one is more viscous?

Liquid A

10G.M. Homsy, Multimedia Fluid Mechanics, Cambridge Univ. Press

Liquid B

11G.M. Homsy, Multimedia Fluid Mechanics, Cambridge Univ. Press

The puzzle solved!

In liquid A the radish moves even after we have stopped rotating the vessel.

In liquid B the radish stops immediately after rotation is stopped.

Liquid B is the Very Viscous Liquid!

Motion of the Very Viscous Liquid has been damped very quickly!

5. Races of balls in liquids

Water HoneyOil

All those liquids have similar density.

Glycerine

START!

5. Races of balls in liquids

Water HoneyOil

All those liquids have similar density.

Glycerine

WaterViscosity = 1

HoneyViscosity =

20 000-100 000

OlejViscosity = 100

Comparison of falling times

GlycerineViscosity = 1000

Very short Short Loong

VeeeryLooong

1. To make the Very Viscous Liquid move, one has to push it hard constantly.

2. Motion of the Very Viscous Liquid is damped very quickly.

3. The more viscous the Very Viscous Liquid is, the slower the ball falls.

Wanted: Very Viscous Liquid

Photofit portrait: