Discretization of the Reynolds Equation
The Reynolds equation for steady state condition is given by;
x
(1)
h
h p
12 u
x
x
3
~
Where
~
u
(2)
ua ub
2
Assuming constant density and viscosity equation (1) can be written as;
(3)
3 p
h
h 12 u
x
x
x
~
Viscous Flow
Now we will concentrate on the aspects of fluid
mechanics that are important in understanding of fluid
film lubrication
Four aspect of viscous flow are important
Fluid viscous resistance increases with the deformation rate.
Making a fluid
Surface Topography
Machine surfaces no matter how smooth to the
naked eye are rough microscopically
Surface roughness plays a major role in tribology
In fact a major portion of the cost associated with
tribological contacts is due to surface preparatio
ReynoldsEquation
The NS in cartesian coordinate system is given by;
Du
p 2
u u v u w
gx
a 2
x 3 x
x x y y x z z x
Dt
gy
p 2
v u v v w
Dv
a 2
y 3 y
y y x y x z z y
Dt
p 2
w u w v w
Dw
gz
a 2
z 3 z
z z x z x y z y
Dt
Theaboveequationsar
Regimes of Lubrication
A lubricant is a type of substance which can be brought into the contact of loaded rolling /
sliding bodies to control friction and wear. Most lubricants are some type of fluid (e.g. mineral
and synthetic oils, etc.); however, there
Contact and Internal stresses
Load supported over a microscopic area of contact results in high stresses. This occurs
when force is transmitted through bodies in contact. Two stationary ellipsoidal bodies in
contact under a static load will generate an el
Mixed EHL Lubrication There are situations where both boundary lubrication and full film lubrication play an important role in the overall lubrication of the contacting bodies. The lubrication regime between boundary and elastohydrodynamic lubrication is
Bearing Materials
The main factor affecting the successful
operation of machine elements is the choice
of materials used
Bearing materials should have especial
characteristics if they are to successfully
support load and allow relative motion in the
mec