W. G. Pritchard Lab Seminar: 4:00-5:00 PM, 101 Osmond Laboratory **Tuesday September 30, 2003** Elliptic functions and wave interactions: some interesting problems David Hill Department of Civil & Environmental Engineering Penn State University Abstract: Water waves can be resonantly forced either by external sources or by interactions between waves. While it lacks the capability to predict wave breaking, weakly-nonlinear analysis is a powerful tool in analyzing these problems. Generally, an equation describing the evolution of the amplitude in time and / or space can be derived for each wave present. In some cases, these equations can be solved analytically in terms of Jacobian elliptic functions. Two problems will be discussed. The first is concerned with the generation of seiches in a body of water in response to horizontal periodic forcing. A natural application is the prediction of the performance of fluid storage containers and small water-supply reservoirs during a seismic shaking event. The second problem is concerned with the generation of interfacial waves by surface waves. In this case, the analysis may help to understand the processes controlling the depth of the oceanic mixed layer and the resuspension of fine-grained sediments in estuaries.