“…However, for the free boundary problem, the well-posedness theory, even the local one, seems far from being well understood. Only some a priori estimates and the local well-posedness were obtained under a special boundary condition (such as p = 0, F T n = 0), see [17,27,16,18,41]. To the best of our knowledge, the problem of the local existence under the force balance condition (1.2) 2 was left open.…”