Special problem $1$

Question

For a $2-$D$,$ vortex flow,

$u_r=0$

$u_{}=\frac{K}{r}$

a$)$ Is this a "free vortex" or "forced vortex"?

b$)$ Does "stream function" exist for this flow? Why?

c$)$ Does "velocity potential" exist for this flow? Why?