Consider the flow of a fluid between two solid plates under the influence/application of a force in X-direction on the top plate.
The bottom plate is stationary. The top surface of the fluid has a constant velocity,
It has been experimentally demonstrated that in such case ‘no–slip' condition exists. The fluid layer in contact with the bottom solid surface will be stationary, whereas the layer in contact with the top solid surface will move at the velocity, . The velocity profiles between the plates will be linear.
(Fig. 2a)
As shown in figure 2a, the fluid element of length at time becomes at time, . Difference in the displacements of Q and P to , respectively, is because of different velocity at
of length 
at time 
becomes 
at time, 
. Difference in the displacements of Q and P to 
, respectively, is because of different velocity at 
