Solitary water wave interactions in a wave channel

Experimental research on the interaction of two co-propagating solitary water waves was carried out, comparing it with the KdV Equation two-soliton solution. Experiments were conducted in a wave channel of width 0.8m, with a 30m length available for the interactions, at a water depth of $h=0.16$m. Solitary waves were generated using a piston wave maker. The higher wave height $a_2$ was fixed, with the parameter $\alpha_2=a_2/h\approx 0.5$; several lower wave heights were used, with $\alpha_1\in(0.1,0.3)$. Surface displacements were measured in fixed locations by resistive probes. The interactions were found to be solitonic, which is predicted by KdV theory. Graphs of surface level vs. time were compared with the KdV two-soliton solutions fitted to the initial wave profiles. Experimental graphs generally differed with theoretical on phases. When heights $a_1$, $a_2$ were comparable, KdV theory acceptably described the qualitative behavior of the interaction. However, when $a1/a2$ was relatively low, the second half of the interaction was more complicated experimentally than theoretically.