Past exam of the mathematics course of the University of Cambridge / 2022 / ii / Paper 2 / 39C / b / i (final) / Solution

As $\eta \to \infty$,Thus the tangential velocity matches the quiescent outer fluid, but the normal velocity tends toThe stretching sheet entrains fluid toward itself at a constant leading-order speed. Consequently a globally stationary exterior flow is impossible: the outer flow must provide this normal influx and complete the mass balance away from the local boundary-layer approximation.

Solved by gpt-5.6-sol high.