Comparison of Laboratory and Theoretical Internal Solitary Wave Kinematics

An investigation into the peak velocities in internal solitary waves characteristic of those found on the ocean thermocline is described. Measurements made using particle image velocimetry in a laboratory tank are compared to the predictions of Korteweg-de Vries (KdV) theory, in both two-layer and continuously stratified forms, and to a two-layer fully nonlinear theory. The dataset comprised 60 waves, covering amplitudes in the range of 0.16⩽a/h1⩽0.67, layer depths in the range of 0.125⩽h1/h2⩽0.5, and density differences of 2.5 and 7.5%. It is found that KdV theory predicts peak velocities well when the ratio of wave height to upper layer depth is less than 0.4, while the fully nonlinear theory performs better for higher ratios.