Fluent simulation of a damaged ship, with multiphase, freesurface and open channel

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• Last Post 14 January 2019
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nTTs posted this 12 January 2019

Hello everyone,

My name is Cristi and I'm fairly new to this forum, at least as a registered user. If you've taken the time and patience to read this post, thank you.

I am working on a thesis about the behavior of damaged vessels, e.g. global strength, maneuverability, local strength etc. I am fairly new to ANSYS so I took my time to do some research, tutorials and a few tests.

To briefly summarize the thesis, I am trying to find a proper way of analyzing different damage scenarios, providing close to over-night solutions and then using the pressure data obtained from the flow analysis to ANSYS mechanical, where I can asses the impact on the steel ship structure. I am unsure whether this is actually possible directly, but I have read about this being a possibility.

As such, the first step would be to run some FLUENT analyses and then compare the results to experimental data that I already have thanks to Japan's NMRI, confirm that the method provides reliable results, then move on to the next step. As you can see, it's a fairly industry-oriented thesis. The normal practice is the other way around, where you would run different variations of a design and the best one or the top few would go into the towing tank. In the shipbuilding industry, damage a vessel is treated mostly statistical or with empirical formulas.

To get to the point of the post, I first need to get past the Fluent simulation. There is an older tutorial for Fluent 13.0 I believe, called "Heave and Pitch Simulation of Ship hull moving through head sea waves". I have the tutorial but not the associated hull-2dof.msh mesh file and six_dof_property.c UDF function. Is there any way to still get these, even if they were made for an older version of FLUENT? I would see how a proper mesh for this kind of analysis should look like, and try to understand and perhaps write an UDF function for a 3D analysis.

I plan on using the Open Channel analysis for fluent, with a multiphase water/air analysis, with the VOF model. Is that suitable for what I'm trying to achieve? Is an open channel analysis different than doing a regular analysis and just using an UDF function to simulate the incoming regular waves? I believe in the area of the hole, the mesh will have to be highly refined to capture all the details of what happens there and perhaps set the field for a local strength analysis in the damaged compartment.

Would a mesh consisting of a single solid for the water and air domains, in which the hull has been cut out suffice?

That is all for now, thank you to all that have read this far. Once I get started I will update this post with results and comments.

nTTs posted this 14 January 2019

Thank you.

kkanade posted this 14 January 2019

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abenhadj posted this 13 January 2019

1/Open Channel Wave is suitable for your simulation goals.

2/Fluid mesh will contain the outer ship hull + fluid domain for air and sear

3/Unfortunately as ANSYS Stuff I won't be able to share any non-supported tutorials.

Best regards,

Amine