Question

The potential flow theory assumes that the flow is ______.

• A. irrotational, inviscid and incompressible
• B. rotational, viscous and incompressible
• C. rotational, viscous and compressible
• D. irrotational, inviscid and compressible

Hint:

Recall the three conditions needed for a velocity potential function to exist.

Answer 1

The Correct Option is A

Step 1: Recall why potential flow is used.
Potential flow theory is a simplified model used to study flow around ship hulls and other bodies without solving the full viscous flow equations.

Step 2: List the three assumptions it needs.
It assumes the fluid is inviscid, so no friction between fluid layers, incompressible, so density $\rho$ stays constant, and irrotational, so the vorticity $\nabla \times \vec{v} = 0$ everywhere.

Step 3: Match with the given options.
Only the option listing irrotational, inviscid and incompressible together matches this standard set; the other options mix in rotation, viscosity, or compressibility.

Final Answer:
These three conditions together allow a single velocity potential to exist. \[ \nabla \times \vec{v} = 0, \quad \mu = 0, \quad \rho = \text{constant} \]