·        

The first part in the RHS of Eq. (5.3.3) is the solution for Couette wall-driven flow whereas the second part refers to the solution for Poiseuille pressure-driven flow . The actual velocity profile depends on the dimensionless parameter

(5.3.4)

Several velocity profiles can be drawn for different values of p as shown in Fig. 5.3.2. With , the simplest type of Couette flow is obtained with no pressure gradient. Negative values of p refers to back flow which means positive pressure gradient in the direction of flow.

Fig. 5.3.2: Velocity profile for a combined Couette-Poiseuille flow between parallel plates.