Past exam of the mathematics course of the University of Cambridge / 2005 / ii / Paper 1 / 36E / i / Solution

For $2\alpha <\pi /2$, ${\lambda }_0>2$ and ${\lambda }_1>6$. Every harmonic correction decays faster than $r^2$ at the corner, so the $r^{2}f(\theta )$ particular solution is the leading corner velocity. It is positive inside this acute wedge and the velocity gradient tends to zero at the vertex.