The aim of the present study is to provide a rigorous analysis of the water wave modelling capabilities of the advanced multipurpose CFD code Fluidity. This code has been developed at Imperial College London over a large number of years and benefits from an open source GNU license. In contrast to similar studies adopting closed-source in-house or commercial solutions, the results presented herein may be verified by any computer literate reader. The investigation focuses on the simulation of gravity water waves; their detailed understanding being fundamental to the design of many offshore (marine) solutions, including the emerging fields of wave energy conversion and floating offshore wind applications. Both small amplitude (linear hydrodynamics) and finite amplitude (nonlinear hydrodynamics) regular waves are simulated in a 2D Numerical Wave Tank (NWT). First, and assessment of the NWT's capabilities in accurately modelling wave propagation and wave energy conservation of linear waves is undertaken. Subsequently, the simulated wave field is directly compared with results obtained from linear wavemaker theory. For the purpose of the nonlinear wave investigation, two wave generation techniques are adopted, and comparisons with a high-order potential flow theory are made. The overall agreement between the simulation results and theory was found to be very good.@en

A rigorous analysis of the water wave modeling capabilities of the advanced multipurpose CFD code Fluidity is presented. The study focused on the simulation of gravity water waves; their detailed understanding being fundamental to the design of many offshore (marine) solutions, including the emerging fields of wave energy conversion and floating offshore wind applications. Both small amplitude (linear hydrodynamics) and finite amplitude (nonlinear hydrodynamics) regular waves were simulated in a two-dimensional Numerical Wave Tank. To study the nonlinear wave, two wave generation techniques were adopted, and comparisons with a high-order potential flow theory were made. The wave group and the wave phase velocities showed excellent agreement with analytical solutions. The generation of nonlinear water waves was implemented using two different methodologies, i.e., a depth-constant piston-mode velocity distribution and a fifth-order Stokes velocity distribution. In both cases, a qualitative analysis indicated very good agreement with the expected fluid behavior. This is an abstract of a paper presented at the Proceedings of the Twenty-Second International Offshore and Polar Engineering Conference (Rhodes, Greece 6/17-22/2012).@en

Mass balance analysis of ice sheets is a key component to understand the effects of global warming. A significant component of ice sheet and shelf mass balance is iceberg calving, which can generate large tsunamis endangering human beings and coastal infrastructure. Such iceberg-tsunamis have reached amplitudes of 50 m and destroyed harbours. Calving icebergs interact with the surrounding water through different mechanisms and we investigate five; A: capsizing, B: gravity-dominated fall, C: buoyancy-dominated fall, D: gravity-dominated overturning and E: buoyancy-dominated overturning. Gravity-dominated icebergs essentially fall into the water body whereas buoyancy-dominated icebergs rise to the water surface. We find with unique large-scale laboratory experiments that iceberg-tsunami heights from gravity-dominated mechanisms (B and D) are roughly an order of magnitude larger than from A, C and E. A theoretical model for released iceberg energy supports this finding and the measured wave periods upscaled to Greenlandic outlet glaciers agree with field observations. Whilst existing empirical equations for landslide-tsunamis establish estimates of an upper envelope of the maximum iceberg-tsunami heights, they fail to capture the physics of most iceberg-tsunami mechanisms.@en