Double-fluid steady filtration flows in near-shore water-bearing strata

Two-dimensional stationary problems of filtration of a fluid having unknown contact (free) boundaries with fixed fluids of different density (water–air and salt and fresh waters) are studied. The paper considers various applied problems of this type, which are encountered, for example, in description of filtration in a water-bearing stratum of fresh water bordering on marine or salt ground waters/ the problems of a fresh-water lens, a bottom-water cone near an imperfect well, equilibrium of two interfaces reaching drainage, etc. Unique solvability is proved for a wide class of contact problems of filtration of fluids of various density in porous channels with known parts of boundaries in the form of finite or infinite polygons.