Numerical modelling of tsunami impact pressure on a vertical wall

The recent occurrences of large tsunamis and its impact on the nearshore structures necessitate revisiting the estimate of tsunami induced forces. Tsunamis often approach the shore in the formation of bores depending on the bottom bathymetry. Many previous studies focused on the motion of bore front and the associated flow field with reference to different configurations on the downstream. The induced pressures on port and coastal defence structures were also measured in a few laboratory experimental studies. In this study, the tsunami front is idealized as a bore front, and the bore induced impact pressure is evaluated in terms of the pressure impulse. The governing equation and, the free surface and wall boundary conditions are cast in the finite element system to solve for the pressure impulse. The pressure impulse imposes the requirement of sudden changes in the front velocity before and after the impact on the structure. The turbulent bores when the relative height of bore front with reference to the shallow water depth in front of it is large, can produce large impact pressures on the structures. The computed impact pressures are analysed and compared with the data from the laboratory experiment. The influence of the bottom clearance of the elevated building on its impact is discussed.