Stability of the Favorable Falkner-Skan Profiles for the Stationary Prandtl Equations

The (favorable) Falkner-Skan boundary layer profiles are a one parameter ($\beta \in [0,2]$) family of self-similar solutions to the stationary Prandtl system which describes the flow over a wedge with angle $\beta \frac{\pi }{2}$. The most famous member of this family is the endpoint Blasius profile, $\beta =0$, which exhibits pressureless flow over a flat plate. In contrast, the $\beta >0$ profiles are physically expected to exhibit a $\mathit{\text{favorable}}\mathit{\text{pressure}}\mathit{\text{gradient}}$, a common adage in the physics literature. In this work, we prove quantitative scattering estimates as $x\to \mathrm{\infty }$ which precisely captures the effect of this favorable gradient through the presence of new ``CK" (Cauchy-Kovalevskaya) terms that appear in a quasilinear energy cascade.