Hydrodynamical Stability of Salt Wedge

The hydrodynamical stability of a salt wedge is examined in terms of a simple example consisting of two layers of fluids in uniform shear. The upper fluid is lighter than the lower fluid and is bounded by a free surface at the top. Salt wedge stability has been studied through the growing and decaying modes of the system. Neutral stability curves have been established in terms of the dimensionless parameter, the wave number, and the thickness ratio of the upper layer to the shear layer. The stabilizing influences of the free surface and the interface have been found to be dependent on the wave number. Critical values of the dimensionless parameter have been predicted to occur between 0.1 and 0.6 (depending on the thickness of the upper layer), below which stable flows can persist; its minimum value (0.1) agrees with the experimental measurements made by Esch.