What are lubricants explain the theories of lubrication?

In fluid dynamics, lubrication theory describes the flow of fluids (liquids or gases) in a geometry in which one dimension is significantly smaller than the others. Free film lubrication theory is concerned with the case in which one of the surfaces containing the fluid is a free surface.

What are the two theories in existence regarding the application of lubricants on a surface?

Basically, lubrication is governed by one of two principles: hydrodynamic lubrication and boundary lubrication. In the former, a continuous full-fluid film separates the sliding surfaces. In the latter, the oil film is not sufficient to prevent metal-to-metal contact.

What is lubrication forces?

Lubrication force is a hydrodynamic viscous force arising from radial pressure in the interstitial fluid being squeezed from the space between two close solid surfaces.

What is mechanism of lubrication?

The authors state that the coefficient of friction between two rubbing surfaces is influenced by a very large number of variables, the most important being, in the case of an oiled journal, the nature and the shape of the surfaces, their smoothness, the clearance between the journal and the bearing, the viscosity of …

What are two examples lubricants?

A lubricant is a substance which introduced to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. For example – motor oil, friction modifier, friction additive, gel, silicons, flourocarbons, ect.

Who invented lubrication theory?

In addition, Sir Isaac Newton (1687) discovered the fundamental law of viscous resistance under- lying the theory of lubrication, according to which the shearing stress is proportional to the rate of shear (Refs. I, 21. 27). The constant of proportionality was later called viscosity.

Who first gave the theory of hydrodynamic lubrication?

O. Reynolds
History of lubrication theory goes more than a century back to 1886 when O. Reynolds published famous equation of thin fluid film flow in the narrow gap between two solids (Reynolds 1886). This equation carries his name and forms a foundation of the lubrication theory.

What are the application of lubricants?

Oil, water, and oil emulsion are used as cutting fluids. These liquids are used to cool as well as to lubricate surfaces. Emulsions of oil in water are most widely used as cutting fluids. Lubricants are also used as cutting fluids in cutting, grinding, trading, and drilling of the metals.

What is lubrication and types of lubrication?

There are three different types of lubrication: boundary, mixed and full film. Each type is different, but they all rely on a lubricant and the additives within the oils to protect against wear. Full-film lubrication can be broken down into two forms: hydrodynamic and elastohydrodynamic.

Which is an example of a lubrication theory?

In fluid dynamics, lubrication theory describes the flow of fluids (liquids or gases) in a geometry in which one dimension is significantly smaller than the others. 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.

How does lubrication theory relate to film thickness?

For very thin films (thickness less than one micrometre ), additional intermolecular forces, such as Van der Waals forces or disjoining forces, may become significant. Mathematically, lubrication theory can be seen as exploiting the disparity between two length scales. The first is the characteristic film thickness, .

What is the purpose of internal flow lubrication theory?

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.