Use of OpenFOAM in Modelling of wavestructure 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
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
1.
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
Thank you!