Observations of Wave Motion and Upstream Influence in a Stratified Fluid

The disturbances created by the motion of a vertical flat plate within the density-gradient region between two superimposed liquid layers were examined both experimentally and numerically. An upstream influence, which resulted from a balance of inertial and gravitational forces, was observed, and it was possible to predict the behavior of this influence with the numerical model. The prediction included a description of the propagation of the upstream influence to steadily increasing distances from the flat plate and the shapes and magnitudes of the velocity profiles.