Bounds for solutions to the problem of steady water waves with vorticity
  The two-dimensional free-boundary problem describing steady gravity waves with vorticity on water of finite depth is considered. Bounds for stream functions as well as free-surface profiles and the total head are obtained under the assumption that the vorticity distribution is a locally Lipschitz function. It is also shown that wave flows have counter-currents in the case when the infimum of the free surface profile exceeds a certain critical value. 
Vladimir Kozlov, Nikolay Kuznetsov
math-ph math.MP