Question

What is the nature of the flow having a velocity potential?

(a) Rotational

(b) Irrotational

(c) Inviscid

(d) Viscous

This question was posed to me in an international level competition.

Question is from The Velocity Potential Equation in chapter Velocity Potential Equation of Aerodynamics

Answer 1

The correct answer is (b) Irrotational

For explanation: For irrotational flow, curl of velocity vector yields zero. In case the curl of any vector is zero i.e.∇ × V = 0, where V is a vector, it is also expressed in the form of ∇ζ where ζ is a scalar function. In case of irrotational flow, velocity potential ϕ is the scalar function. Hence if the flow has a velocity potential, it automatically implies that it is irrotational.