Question

The stream function for a two - dimensional flow is given by $\Psi =2xy$. The velocity at (2,2) is

• A. $4\sqrt{2}$
• B. 4
• C. $2\sqrt{2}$
• D. $\sqrt{2}$

Answer 1

The correct option is A

$4\sqrt{2}$

(a)

$u=-\frac{\partial \Psi }{\partial y}=-2x$

$andv=\frac{\partial \Psi }{\partial x}=2y$

At point (2,2)

u = -4 units and v = 4 units

$\therefore V=\sqrt{u^2+v^2}$

$=\sqrt{{(-4)}^2+{\left(4\right)}^2}$

$=4\sqrt{2}units$