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Physical experiments were conducted in an impounded channel to study the propagation of negative surges advancing in still water and evolution of undular surges against an instantaneously varied flow. The results demonstrated that the initial wave height of a negative surge could be accurately predicted using the simple wave solution of the Saint–Venant equations. Moreover, the wave height evolution during surge propagation could be satisfactorily described using the solution by Ippen and Kulin. The main characteristics of an undular surge were strongly correlated to the surge Froude number and turbulent boundary layer development at the toe of the surge. However, the occurrence of wave breaking at the first wave crest was independent of the inflow conditions and was close to the breaking criterion for solitary waves. Furthermore, the present results indicated the largest turbulent Reynolds stress components beneath the wave crests of an undular surge. [ABSTRACT FROM AUTHOR]

The interaction of nonbreaking and breaking undular surges with a vertical wall is experimentally investigated. The results for nonbreaking undular surges demonstrate that the maximum run-ups agree quantitatively with the predictions of solitary wave theory. During the run-up of a nonbreaking undular surge, the maximum dynamic pressure on a vertical wall occurs at an elevation in the vicinity of the quiescent water level. Both the maximum dynamic pressure and maximum wall force can be accurately estimated from the wave amplitude of the incident surge. By contrast, the breaking surge interactions result in significant amplifications of maximum run-ups and tend to yield extremely high impact pressures at elevations significantly above the still water level. The experimental results indicate the occurrence of extreme impact events for normalized maximum pressures exceeding 1.13. Based on these experimental results, a numerical method is employed to discuss the analogy between a nonbreaking undular surge and a solitary wave. In general, the present results show that the leading front of a nonbreaking undular surge during its initial wave evolution can be satisfactorily described using the solitary wave equation. [ABSTRACT FROM AUTHOR]

Physical experiments were conducted in a long water wave tank over a wide range of still water depths to study the evolution and runup of nonbreaking undular surges generated by the release of a given volume of water. The results demonstrated that the wavefront of a nonbreaking undular surge closely matched that of the corresponding solitary wave of the same height. The wave celerity of the surge could be accurately predicted using the solitary wave theory. Two distinct wave stages existed in the evolution process of a nonbreaking undular surge based on the wave shape asymmetry. The wave stage transition could be approximated as a surge Froude number equal to 1.15. The wave amplitude and steepness of undular surges were in reasonable agreement with the linear wave theory for surge Froude numbers greater than 1.20. However, the wave length data presented a different pattern to that predicted by either the linear wave theory or the solution of the Boussinesq equation. Furthermore, the maximum surge runup on a vertical wall was in excellent agreement with the solitary wave theory. This study provided new insights into the quantitative behavior of nonbreaking undular surges. [ABSTRACT FROM AUTHOR]