Le problème de Helmoltz pour des obstacles peu réguliers

The classical Helmholtz model for wakes behind an obstacle in perfect fluid mechanics boils down in complex analysis into a Riemann problem with free boundary, the free boundary being the wake and being such that the Riemann map parametrizes it as arclength parametrization. We generalize a method due to Coifman and Meyer [CM] to solve this problem for a class of non-smooth obstacles.