Abstract: We investigate reversal and recirculation for the stationary Prandtl equations. Reversal describes the solution after the Goldstein singularity, and is characterized by spatio-temporal regions in which \(u > 0\) and \(u < 0\). The classical point of view of regarding the Prandtl equations as an evolution \(x\) completely breaks down. Instead, we view the problem as a quasilinear, mixed-type, free-boundary problem. Joint work with Nader Masmoudi.