Question

In plane Couette flow, the flow is generated by:

• A. Pressure gradient
• B. Gravity
• C. Relative motion between two plates
• D. Viscous heating

Hint:

In Couette flow, the flow is driven by the relative motion between two plates, one moving and one stationary. It is a classic example of shear-driven flow.

Answer 1

The Correct Option is C

In plane Couette flow, a flow of fluid is generated between two parallel plates. One of the plates is fixed while the other moves at a constant velocity. The flow is induced primarily by the relative motion between the two plates, which sets up a shear stress in the fluid. This is the defining characteristic of Couette flow.
- A pressure gradient can induce flow in other types of flow (like in pipe flow), but in Couette flow, there is no pressure difference driving the flow.
- Gravity does not play a significant role in plane Couette flow as it is primarily driven by the motion of the plates, not by gravitational forces.
- Viscous heating is a result of the internal friction in the fluid as it flows, but it is not responsible for generating the flow itself in Couette flow.
- The flow in Couette flow is generated due to the relative motion between the two plates, which causes the fluid to experience shear stress and consequently, flow.
Thus, the correct answer is the relative motion between two plates.