“…One of the classical methods to deal with free boundary problems is to exploit potential theory in order to reformulate the problem into a new contour dynamics equation, which will be typically nonlocal and strongly non-linear. Let us mention that this kind of approach has been extensively and successfully used in other free boundary problems in fluid dynamics to show well-posedness (see [3,8] for the vortex patch, [11] for water waves, [30,18,17] for the SQG sharp-front, [12,16] for the Muskat problem and [19,9] for the Peskin problem). Furthermore, it has been applied to prove singularity formation for the water waves, the SQG sharp-front and the Muskat problem [6,4,29,18,5].…”