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Use of OpenFOAM in Modelling of wave-structure interactions. Lifen Chen Supervisors: Dr JunZang , Dr Andrew Hillis , Prof Andrew Plummer Architecture and Civil Engineering department University of Bath lc499@bath.ac.uk. Bath HPC symposium 4 th , June, 2013 Bath, UK. Background.
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Use of OpenFOAM in Modelling of wave-structure interactions Lifen Chen Supervisors: Dr JunZang, Dr Andrew Hillis, Prof Andrew Plummer Architecture and Civil Engineering department University of Bath lc499@bath.ac.uk Bath HPC symposium 4th, June, 2013 Bath, UK
Background Ocean waves: wind generated waves Irregular waves Intermediate and deep waters Approximations Regular waves: sine/ cosine function
Background Wave motion: Wave amplitude/elevation Water depth Wave length
Background • Computational Fluid Dynamic (CFD): OpenFOAM • Open Source C++ library • Suitable for use in wide ranges of problems
Parallel processing capability of OpenFOAM • Default • Domain decomposition • openMPI • Terminal commands • decomposePar • mpirun--hostfile <machines> -np <nProcs> • <foamExec> <otherArgs> -parallel > log & • reconstructPar
Cases Computational domain: 30m × 2m × 1.01m (half domain) 8 cases: various wave parameters Zang, J. and Taylor, P. H etal.(2010) Steep wave and breaking wave impact on offshore wind turbine foundations—ringing revisited 25th IWWWFB, China
Computational Cost (Multi-cores) Cells: 15712120 Cores: 4 cores Computational time: 5 days Size of output files: 90GB Cases: ? Static mesh Dynamic mesh
Results Has been applied in ocean engineering successfully. Can predict wave loading on the fixed structure correctly. In adaptions of the source code… A series of trials: Boundary conditions mesh type and resolution wave parameters…..
Running in parallel (Aquila) • OpenFOAM-2.1.0 vs. OpenFOAM-1.5 PC vs. Aquila • testing • Boundary conditions: • attempted: totoalPressure for output boundary • PC: stable Aquila: dump after 7s • modified to: zeroGradient • PC: stable Aquila: stable • 2. Running the case • PC: 4 cores Aquila: 4 processors
Running in parallel (Aquila) t = 5s t = 10s t = 15s t = 20s t = 25s Green line : PC results, red line: Aquila results
Future work • Simulation interactions between waves and floating bodies. • dynamic mesh • Simulation interactions between waves and real WECs. • complex geometries and structures’ shape Increase computational cost