Dr John-Paul Latham  and Dr Jiansheng Xiang use numerical simulation for coastal engineering applications. In future, numerical simulation will improve design methods for protection against the higher waves that will reach our shores because of sea-level rise and the more extreme storms we should expect with climate change. 

Breakwater with 20 tonne concrete units
Breakwater with 20 tonne concrete units, courtesy of CLI

Here, simulation is used to place 20 tonne concrete units realistically on a layer of rocks. The technology that we have developed, Solidity, allows us to pack the irregular-shaped particles or units in a realistic way. We can then add the hydraulic forces due to buoyancy and wave action to the ‘dry’ forces that govern the equilibrium and stability of the solid pack - to simulate the movement of complex-shaped massive interlocking units during storm wave action.

Numerical breakwater with mechanical detail
Numerical breakwater with expanded view showing level of geometrical and mechanical detail achievable – down to the sacrificial friction studs on this sophisticated unit

Our software also allows us to model the stresses and forces on whatever type of concrete units the designer is thinking of using. For example, the likelihood such stresses will lead to unit breakages can be investigated. Much will depend on the location and orientation of the block, its interlocking with neighbours and the how the fluid moves around the units. So, the simulation allows us to consider the structural integrity of the concrete units, if they are packed correctly, and the impact of the wave.

Storm simulation
Snapshot during a storm simulation – arrows and colours showing the velocities of those vulnerable units that become displaced during this surging wave action


Our technology gives us an extra level of accuracy and it can be used in a range of industrial applications. It is applicable on a much smaller scale, for example catalyst packing. 

Catalyst Packing

Catalyst Packing: here, we show how we compute the contact interaction and motion of bodies and present two packing simulations by Solidity - a single-holed pellet pack and a multi-holed grooved pack

Solidity is an Open Source general purpose, two and three dimension finite element–discrete element solid mechanics code. The Finite-Discrete Element Method (FEMDEM) combines the ability to model multi-body particle interaction and motion (i.e. Discrete Element Method, DEM) with the capacity to model internal deformation within any arbitrary shaped body (Finite Element Method, FEM). It has been successfully applied to breakwater models and catalyst packing, for example.

FEMDEM allows the individual particle behaviour governed by DEM formulations (particle detection and interaction) to be combined with an ability to discretise any particle into considerably smaller deformable finite elements. This allows us to introduce any complex particle shape and hence not be reliant on approximations based on overlapping clustered spheres which form the basis of many DEM models.