Lubrication theory

An example is the flow above air hockey tables, where the thickness of the air layer beneath the puck is much smaller than the dimensions of the puck itself.

Internal flow lubrication theory has many industrial applications because of its role in the design of fluid bearings.

Here a key goal of lubrication theory is to determine the pressure distribution in the fluid volume, and hence the forces on the bearing components.

In that case, the position of the free surface is itself unknown, and one goal of lubrication theory is then to determine this.

Examples include the flow of a viscous fluid over an inclined plane or over topography.

[citation needed] Mathematically, lubrication theory can be seen as exploiting the disparity between two length scales.

An important application area is lubrication of machinery components such as fluid bearings and mechanical seals.

Coating is another major application area including the preparation of thin films, printing, painting and adhesives.

Biological applications have included studies of red blood cells in narrow capillaries and of liquid flow in the lung and eye.