Analysis of stagnation point flow toward a stretching sheet

There has been much recent interest in the stagnation point flow of a fluid toward a stretching sheet. Investigations that may include oblique stagnation flow and heat transfer to a horizontal plate all involve the same boundary value problem (BVP):f^‴ + ff^″ - (f^′)² + b² = 0,f (0) = 0, f^′ (0) = 1, f^′ (∞) = b .Here b is the ratio of the stagnation flow strain rate to the stretch rate of the sheet. Through numerical analysis of the problem, several authors have conjectured the existence of a solution for all values of b > 0. In this note we present numerical evidence that a second solution exists for 0 < b < b_c ≈ 0.16906. Further we present a mathematical proof that for all b > 0 there exists a monotonic solution to the BVP and if b > 1, this solution is unique. If b < 1 it can be shown that any further solutions cannot be monotonic and the second solution found here numerically is non-monotonic. The asymptotic behavior of solutions near b = 0 and 1 is also presented. Finally, a stability analysis is performed to show that solutions on the upper branch of the dual solutions are linearly stable, while those on the lower branch are linearly unstable.