Success Story: Supercomputer Applications in Hydrodynamics

NCC presenting the success story

The National Competence Centre of Bulgaria (NCC-Bulgaria) in the area of High-Performance Computing (HPC), High-Performance Data Analytics (HPDA) and Artificial Intelligence (AI) has the goal to enhance and develop the competences of the Bulgarian computational community, making full use of EuroHPC resources and the EuroCC partnership.

The NCC-Bulgaria is built by a consortium coordinated by the Institute of Information and Communication Technologies at the Bulgarian Academy of Sciences (IICT-BAS), and two members, Sofia University “St. Kliment Ohridski” (SU), and University of National and World Economy (UNWE). The three partners carry diverse technical and scientific background in the area of HPC and ICT in general, so as to ensure achievement of the project objectives and guarantee the overall success.

The partners collaborate with Sofia Tech Park, where the Discoverer EuroHPC supercomputer is operating.

Technical/scientific Challenge:

The subject of this investigation is a simulation of the motion of a trimaran/ship in multiphase flow conditions – which is one of the complicated problems in the ship hydrodynamics. One of the challenges is the choice of the number of cells in the generated fine mesh. This number is important in order to receive good simulation. Another challenge is the pre-processing in which grid cells are split proportionally so that simulations can be performed on different CPU cores in order to improve scalability.

Scientific/Business impact:

The scientific impact: Results show a good parallel efficiency up to 4 and 8 nodes. Using a supercomputer Avitohol, the computation time was reduced from a week to a day to simulate a 1-minute video of ship/trimaran motion in the presence of waves and wind. The parallel CFD simulation tests for modelling a trimaran were done to demonstrate the parallel performance of the OpenFoam software and to define efficient usage of Avitohol resources based on the introduced scalability criterion.

The business impact: (i) Study of ship hull elements to decrease drag and regulate the ship’s turbulent flow. (ii) Development of new hull elements with simple and scalable solutions that reduces fuel consumption and environmental impact.

Partners involved in the success story:

The department of Scalable Computing and Applications (SCA) with HPC Centre is one of the departments of IICT-BAS. It manages the HPC centre where is located the supercomputer Avitohol. The department SCA with HPC centre is focused on activities in the development and deployment of Cloud middleware and software components, methods, algorithms, and applications suitable for Cloud and HPC computing systems.

The Bulgarian Ship Hydrodynamics Centre (BSHC) as part of the Institute of Metal Science, Equipment and Technology “Acad. A. Balevski” at the Bulgarian Academy of Sciences (IMS-BAS) is a national research and development centre, operating on a non-profit basis. It has been established in 1976 with the technical and financial support of the United Nations Development Programme (UNDP) and the International Maritime Organization (IMO). BSHC’s mission is to perform fundamental and applied research and train graduate and post-graduate students in the areas of ship hydrodynamics; aerodynamics; ocean and coastal engineering; environmental protection; sea/river crises; sea/river energy utilization and disasters; water transport; national security and defense.

Solution:

The mathematical model includes Navier-Stokes equations. The approximate solution of these equations is performed by the finite element method, using OpenFoam CFD software. The geometry of the trimaran/ship and the corresponding number of cells in the network are provided. With different geometries, the ship “behaves” differently in calm waters and in the presence of multiphase flow (wind/waves). To simulate the motion of a trimaran/ship with certain dimensions, we use OpenFoam CFD software version 5.0, which includes a special library (libwaves.so) for simulating waves. The Rhino 5.0 product is used for the 3D model generation. The total number of cells for generation of the mesh is 9 631 050. To obtain a 3-minute simulation of the ship in calm waters, we need computer time of up to 1-2 weeks using a single server from the Avitohol supercomputer. That is why we had to distribute the calculations in parallel using MPI on several computational nodes in order to obtain a complete simulation.

Benefits:

• Reduction of simulation time by using parallel computations even though the number of cells in mesh generation is several million;
• Improving the stability of a ship/trimaran in calm waters or in multiphase flow (presence of winds and waves) using the fine 3D grid.
• Study of ship hull elements to decrease drag and regulate the ship’s turbulent flow.