Specialist Committee on CFD/EFD Combined methods
CFD offers new possibilities to improve the EFD based predictions, for example with new treatment of scale effects. On the other hand, we can still not in general rely purely on CFD for ship hydrodynamic predictions for commercial or legal purposes. By using the best combination of CFD and EFD, rather than viewing them as competing methods, we can deliver even better prediction. New methods based on EFD/CFD combinations need to have the same confidence level as the existing Recommended Procedures give to the end client today.
The purpose of the committee is to initiate and support the process of introducing combined CFD/EFD methods in ITTC’s procedures, with a focus on the confidence level.
What do we mean by CFD/EFD Combined methods?
There are different scales of combination from mainly EFD to mainly CFD:
- Improve the EFD scaling laws using CFD.
- Use CFD to design experiments.
- Use CFD to understand and quantify scale effects.
- Mixed methods – some components in the prediction chain with CFD.
- Validate CFD solution at model scale for the actual case, then perform full scale CFD.
- Use EFD to validate and improve CFD models in general
Inspiration to researchers
To facilitate the introduction of CFD/EFD Combined method in our community, the Committee has identified several research areas which need to be addressed. In this way, we wish to inspire researchers around the world to contribute to the development.
If you are currently studying related topics, or plan to do so, we would very much appreciate if you could inform us about it. Please contact Sofia Werner.
- Form factor determination with CFD. A benchmark-study is ongoing and we encourage researchers and students to participate. Please contact Sofia Werner for more information.
- Accuracy of CFD is still hindered by errors due to mesh quality and modeling error of the turbulence model. Assist in improving the accuracy especially in full scale Reynolds number by
- Good experimental program for smooth body separation at high Reynolds numbers (higher than model scale).
- Full scale field measurements
- Use database of model scale EFD/CFD, full scale CFD, and sea trials to develop more accurate correlation allowance for extrapolation. The world-wide community collectively has an extensive database that could be studied to derive a better correlation allowance.
- Ability of CFD to predict wind resistance corrections for full scale speed trial corrections. A benchmark-study is ongoing and we encourage researchers and students to participate.
- Shallow water correction based on CFD simulations.
- Scale effects and ability of different CFD methods to predict effect of ESD and local inflow to propeller.
- Skin friction reduction methods with CFD.
- Ability of CFD to predict added resistance in waves and fw.
- Importance of scale effects on wake and rudder force for sea keeping and maneuvering tests.
- Using CFD to plan model test campaign for example selecting most important cases in a sea keeping program.
- Numerical models for ice loads.
- Scale effects and the ability of CFD methods to predict local propeller induced noise.
- Use EFD to tune CFD methods for roll damping, investigate scale effects for roll damping fins.
- Scale effects on appendage drag for calm water speed power predictions.
- Investigate scale effects on maneuvering performance, eg. propeller hull interactions. Design model scale propeller that creates correct propeller loads at model scale?
- Modelling of environmental conditions, could CFD help understand physics involved in interactions when generating model scale waves, wind and current?