results from tow tests as illustrated in Figure 1. Another benefit of CFD is that detailed flow visualisations can be made to investi- gate the complex flow behaviour around the vessels as shown in Figure 2.
CFD input for mooring analysis The current loads on side-by-side vessels have for example been computed for GasAtacama Chile SA within the Floating Storage and Regasification Unit (FSRU) Services Mejillones Sea Port project. This project consisted of the supply and operation of a FSRU, together with its mooring facilities and associated offshore/onshore pipeline to transport regasified LNG from the FSRU to the delivery point located ashore. The LNG transfer was done by a side-by-side opera- tion between the LNGC and FSRU.
For this project, MARIN conducted a moor- ing analysis in time-domain using aNySIM. Current load coefficients were required as input in the time-domain numerical model of the FSRU. These coefficients were deter- mined using MARIN’s CFD code ReFRESCO as accurate results had to be obtained within only a few weeks. Other methods such as wind tunnel tests and tow tests in water would have been more expensive and time consuming. The current loads on both the FSRU and the LNGC were computed for several combinations of draughts. Relative motions between the FSRU and the LNGC and the side-by-side line loads were then calculated in the time-domain, taking the computed current coefficients into account. This project showed that CFD can be successfully applied to provide accurate and reliable input data for time-domain studies in a timely manner.
Figure 2: Flow patterns illustrated by the vorticity distribution around a side-by-side configuration for bow-quartering current.
Figure 3: Results for CY coefficient for an LNG carrier for different water depth (WD) over draft (T) ratios comparing CFD results with experimental results, published in [1]
1. Koop, A., Shallow Water Current Loads on a LNG Carrier Using CFD, OMAE2015-4127, St. Johns, Canada, 2015.
2. Koop, A., Current Loads for Side-by-Side Configuration Using CFD to be published at OMAE2016, Korea, 2016.
3. Koop, A., Bereznitski, A., Model-Scale and Full-Scale CFD Calculations for Current Loads on Semi-Submersibles, OMAE2011-49204, Rotterdam, the Netherlands, 2011. 4. Koop, A., Klaij, C., Vaz, G., Viscous-Flow Calculations for
Model and Full-Scale Current Loads on Typical Offshore Structures, MARINE 2011, IV International Conference on Computational Methods in Marine Engineering Computational Methods in Applied Sciences Volume 29, 2013, pp 3-29.
5. Vaz, G., Waals, O., Ottens, H. Fathi, F., LeSouef, T., Kiu, K., Current Affairs: Model tests, Semi-Empirical Predictions and CFD Computations for Current Coefficients of Semi-Sub- mersibles, OMAE2009-80216, Hawaii, USA, 2009.
report 21
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24
