Construction of Exact Solutions of the Problem of the Motion of a Fluid with a Free Boundary Using Infinite Systems of Differential Equations

We consider the well-known hydrodynamics problem for the planar potential motion of an ideal incompressible fluid with a free boundary without capillarity and propose a method for finding exact solutions based on reducing the boundary-value problems to systems of ordinary differential equations. We obtain two examples of flows: a stationary motion of a heavy fluid over a smooth bottom and a nonstationary motion of a fluid that originally filled a wedge.