The Physics of Fluid

What is a fluid?

• A substance in the liquid or gas phase

• A substance in the solid or gas phase

• A substance in the liquid or solid phase

• A substance in the liquid, solid or gas phase

These are the properties of a liquid, except...

• a liquid takes the shape of the container it is in

• it forms a free surface in a larger container in a gravitational field

• groups of molecules can move relative to each other, but the volume remains relatively constant

• expands until it encounters the walls of the container and fills the entire available space

Viscosity is defined as

• a quantity measure of a fluid’s resistance to flow

• external frictional force that develops between different layers of fluids

• an external resistance of a fluid to motion

• a flow of fluid towards gravity

The flow of high-viscosity fluids such as oils at low velocities is

• Laminar flow

• Turbulent flow

• Transitional flow

• Viscous flow

These are types of flow, except:

• Steady uniform flow

• Steady non-uniform flow

• Unsteady uniform flow

• Standard uniform flow

The NO-SLIP condition is...

• An experimental observation that the velocity of a fluid in contact with a solid surface is equal to the velocity of the surface.

• Valid only for liquids.

• Useful only for very low density gases.

• Indicates that two solids in contact will not slip if the joining force is large