Submarine slides can generate tsunami waves that cause significant damage and loss of life.
Numerical modelling of submarine slide generated waves is complex and computationally
challenging, but is useful to understand the nature of the waves that are generated, and
identify the important factors in determining wave characteristics which in turn are used
in risk assessments.
In this work, the open-source, finite-element, unstructured mesh fluid dynamics framework
Fluidity is used to simulate submarine slide tsunami using a number of different
numerical approaches. First, three alternative approaches for simulating submarine slide
acceleration, deformation and wave generation with full coupling between the slide and
water in two dimensions are compared. Each approach is verified against benchmarks from
experimental and other numerical studies, at different scales, for deformable submarine
slides. There is good agreement to both laboratory results and other numerical models,
both with a fixed mesh and a dynamically adaptive mesh, tracking important features of
the slide geometry as the simulation progresses.
Second, Fluidity is also used in a single-layer Bousinesq approximation in conjunction with
a prescribed velocity boundary condition to model the propagation of slide tsunami in two
and three dimensions. A new, efficient approach for submarine slide tsunami that accounts
for slide dynamics and deformation is developed by imposing slide dynamics, derived from
multi-material simulations. Two submarine slides are simulated in the Atlantic Ocean,
and these generate waves up to 10 m high at the coast of the British Isles.
Results indicate the largest waves are generated in the direction of slide motion. The lowest
waves are generated perpendicular to the slide motion. The slide velocity and acceleration
are the most important factors in determining wave height. Slides that deform generate
higher waves than rigid slides, although this effect is of secondary importance for generated
wave amplitudes.