The two$-$dimensional flow around the pylon of a bridge can be modelled using

elementary solutions of potential flow theory. The superposition of uniform flow with velocity V$\backslash$infty $,$ a source of strength E $($located at the origin$)$ and a sink gives the desired flow field. $($Using the formula E$=-4\mathrm{.}15\_$V$\backslash$infty $*$ a$)$ in the real world, there is separation behind the pylon! As a rudimentary

flow control device, aiming to reduce the drag, the flow behind the pylon is

channelled using simple guide plates located at $($x $=$ a$,$ y $=\backslash$pm $0\mathrm{.}5$a$).$ Still

assuming the potential flow approximations, what should the angles alpha of

the guide plates be to have the flow tangential to the guide plates? Give the

angles in degrees.