Question

In a two-dimensional flow, with its stream function $\psi =2xy$, the velocity at a point (3,4) is

• A. 12.0 units
• B. 10.0 units
• C. 8.0 units
• D. 6.0 units

Answer 1

The correct option is B 10.0 units

(b)

$\psi =2xy$

$u=-\frac{\partial \psi }{\partial y}=-2x=-\left(2\right)\left(3\right)$

=-6 units

$v=\frac{\partial \psi }{\partial x}=2y=2\left(4\right)=8units$

Velocity of (3,4)

$V=\sqrt{{(-6)}^2+{\left(8\right)}^2}=10units$