Project CEEC (Center of Excellence for Exascale CFD)

10/07/2024

• Challenge
• Objectives
• Methods
• Partners

Suction foundations for offshore wind turbines can have a significant risk of erosive failure. Nevertheless, this type of marine foundation is gaining relevance as an environmentally friendly alternative to monopile foundations. However, if the operating suction exceeds a critical threshold during the suction-driven installation, the large hydraulic gradients within the flow network imposed in the seabed may cause a localized erosion of soil channels, which would prevent further installation.

This project shall produce a demonstrator of 3D particle-resolved simulation approaches for a real-scale geotechnical application, focusing at first on model validation with available experimental results (physical model tests in reduced scale), and then on a grand application focusing on a representative cut of the full-scale foundation during the first meters of the suction-driven installation.

This project employs the discrete element method and the lattice Boltzmann method to run a fully-resolved coupled fluid-particle simulation. The simulation is implemented in the highly parallel multiphysics framework waLBerla. EuroHPC JU supercomputers are used to perform large-scale simulations.

Project coordination: Königliche Technische Hochschule
Consortium: 8 international partners from Science
Funding: This project receives funding from the European High Performance Computing Joint Undertaking

In this task, a fluid-solid coupled micromechanical simulation of a seabed foundation will be run using the waLBerla framework for the analysis of localized fluidization (so-called piping erosion) during the installation of a suction bucket for the basement of an offshore wind turbine. The fully-resolved simulation will involve a discrete DEM representation of the solid phase (i.e. the structural element and the single grains of the sandy seabed) and an LBM hydrodynamic model of the percolating water. A preliminary coupled model will at first aim to simulate the results of a physical model test in reduced-scale (validation stage with available laboratory tests), while the grand application in 3D will focus on the local phenomena taking place around a representative cut of the full-scale foundation during the first meters of the suction-driven installation. To enable the latter scenario, a major task will concern at first the creation of the initial seabed conditions in terms of a representative granular fabric involving layered deposition, granular cementation and a realistic state of intergranular forces and relative density throughout the embedment depth. The subsequent simulation of the grain-resolved flow will pose a significant computational challenge. The task will be attacked using the Euler-Lagrangian coupling functionality of waLBerla using geometrically resolved particles that can be generated with specified size and shape distributions. The coupling itself will employ the momentum exchange method which must be additionally improved by lubrication models. For more details, see: https://ceec-coe.eu/localized-erosion/.

Partner

Königliche Technische Hochschule
Aristoteles-Universität Thessaloniki
Barcelona Supercomputing Center
Friedrich-Alexander-Universität Erlangen-Nürnberg
Universität Stuttgart
Universität Umeå
Technische Universität Dänemarks

Funding

European High Performance Computing Joint Undertaking