Question

Consider the following parameters related to fluid flow:

1. Vorticity
2. Velocity potential
3. Stream function
Among these, those which exist both in rotational flows and irrotational flows should include

• A. 1 and 2
• B. 2 and 3
• C. 1 and 3
• D. 1, 2 and 3

Answer 1

The correct option is C 1 and 3

(c)
Stream function is a consequence of continuity equation. Vorticity is defined as

$\overrightarrow{\Omega }=\overrightarrow{\nabla }\times \overrightarrow{V}=2\overrightarrow{\omega }$

$forirrotationalflow\overrightarrow{\Omega }=0$

The velocity potential function is derived from the condition of irrotationality. Thus in rotational flow there will be non-zero vorticity and velocity potential function can not be defined.