Maximum and minimum velocities
The quantitative description of non-dimensional velocity distribution across the channel, depicted by Eq. (26.2a), is shown
in Fig. 26.2b.
- The location of maximum or minimum velocity in the channel is found out by setting
=0. From Eq. (26.2a), we can write
 |
Setting 
gives
gives | 26.2b |
- It is interesting to note that maximum velocity for P = 1 occurs at y/h = 1 and equals to U . For P > 1, the maximum velocity occurs at a location
.
- This means that with P > 1, the fluid particles attain a velocity higher than that of the moving plate at a location somewhere below the moving plate.
- For P = -1, the minimum velocity occurs, at
. For P < -1, the minimum velocity occurs at a location
.
- This means that there occurs a back flow near the fixed plate. The values of maximum and minimum velocities can be determined by substituting the value of yfrom Eq. (26.2b) into Eq. (26.2a) as
 |
 | (26.2c) |
FIG 26.2b - Velocity distribution of the Couette flow
