I have questions about CFD codes (RANS) for marine applications.

I am doing a survey about available codes :

- Fluent - CFX - Cd-Adapco - Comet - Finflo - Flow3D - OpenFoam - others

Which one(s) do you recommend me and why (prices, easy of use, confidence with results, ...).

All comments are welcome.

Thanks to all.

Merry Christmas,

Darwin

"Marine Applications" is a bit broad.

Are you interested in hull design, hull-water interaction, sail design, propulsion details (props, ducted props, pump-jet analysis), ... .

You'll probably get more useful answers if you can narrow your request a bit.

Good luck!

I am interested in hull (planing hull, sailing vessel, large ship, container, ...) and marine propeller calculations.

To compute correctly the drag (and lift) produced by a hull you have to set the correct trim, so hull-water interaction (2 fluids) is essential.

Need advices about the 'best' choice of CFD codes with explanations if possible.

Hope it will help.

Darwin.

I think COMET was pretty much the industry standard for a long while but most of the models from that are now in STAR-CCM+ and STAR-CD I think

ya try out star-cd trial version.

Dear Harry,

could you tell me which companies use Comet for their CFD applications ?

Since Comet is no more developed these companies have switched to ???

Darwin

comet has been absorbed by cd-adapco, comets free surface models have been incorporated in star-cd as far as I'm aware

allan

For a comparison of CFD codes for ship performance predicition, check out: Gothenburg 2000 - A Workshop on Numerical Ship Hydrodynamics, ed. Larsson, L., Stern, F. and Bertram, V.

There was a CFD Workshop in Japan in 2005 that might also be helpful.

Most of the codes are pretty poor at predicting far-field waves and resistance. They seem better suited to prediction of some near-field effects, but they are also very slow.

For a very recent comparison of predictions of CFD-SHIP IOWA 4.00 with experimental results, see: Sakamoto, N., Wilson, R.V. and Stern, F., ``Reynolds-averaged Navier-Stokes simulations for high-speed Wigley hull in deep and shallow water", J. Ship Research, Vol. 51, No. 3, Sept. 2007, pp.\ 187--203.

F. Stern's work is very good because he emphasises validation and verification of CFD codes. The whole field needs more "Penn and Teller" types like Stern and his colleagues.

All the best, Leo.

Word from Adapco when I last spoke to them was that they would continue to support Comet as long as there were still users for it. They have been incorporating most of the methods into their mainstream products, but if you want Comet you can still get it.

it is simple: ask their sales guys to show that the code predicts the "humps and hollows" of the wave resistance around a hull versus the Froude number, especially at Fr=0.33 and Fr=0.4 and that the code conserve the relation 1.25 with the square root of velocity.

It is the equivalent of drag versus Reynolds. Results are well known. Also they should also be able to advise you on boundary conditions and mesh size and turbulence model, setup, etc...Comet could not predict this correctly along the full range or Froude numbers.

Then you will know the best code or a least proceed to a first elimination...then you can select by price or time to mesh.

Good luck.

You're right. For their validation COMET got lucky for the wave heitght or they did a lot of tuning for 1 velocity but then for marine application it is expected that the code works for more than 1 knots value or Froude number. The code must be tested on the full range.

G.