Question

Sketch the stream lines represented by ψ = xy. Also find out the velocity and its direction at point (2, 3).

Answer 1

Velocity:

u=ui+vj

$u=\frac{\partial\psi}{\partial y}=x$

$v=-\frac{\partial\psi}{\partial x}=-y$

At point (2,3):

u=2

v=-3

u=2i-3j