Question

______ gives the velocity component at right angles to a particular direction.

(a) velocity

(b) velocity vector

(c) stream function

(d) pressure line

The question was asked in a job interview.

Origin of the question is Source Flow in section Inviscid & Incompressible Flow of Aerodynamics

Answer 1

The correct choice is (c) stream function

For explanation I would say: Stream function is defined as the scalar function of space and time such that its partial derivative with respect to any direction gives the velocity component at right angles to that direction. It is valid only for 2D flow and is denoted by Ψ.