Learning Forum

[Abhemanyu Palaniswamy Chandrasekaran]

Hello,

I am a beginner to LS-DYNA. I would like to simulate the wake around a ship moving with a constant velocity by using the ALE method with penalty coupling. I have the following queires to begin with.

1. Is ALE method recommended for such simulations involving larger time durations?

2. To begin with a simple numerical simulation, I start with a partially submerged cylinder. Would ALE solver be able to capture the effects of viscous drag and boundary layers?

3. Are there some recommendations to model the water around a floating body (material properties and equations of state) which would particularly suit this simulation?

I am working on my master's thesis regarding ship collisions. I would like to use the ALE method to investigate the collision phenomenon along with the Fluid-Structure Interaction. Is it possible to use a different solver such as the ICFD solver for the initial phase of the ship motion (generating the wake field around the moving ship) and then switch to the ALE solver for the collision simulation.

Thanks & Regards

Abhemanyu

[Reno Genest]

Hello Abhemanyu,

Do you need to model the water in the ship crash simulation? Will the wake have significant effects on the crash results? Do you need to go into the details of drag and boundary layer?

It seems like you have to do a literature review. I think both ALE and ICFD could be used in your case to model the water and the FSI between the ship and water. 

You can search on dynalook.com. Here are some papers that you might find interesting:

https://www.dynalook.com/conferences/11th-european-ls-dyna-conference/impact-marine-aviation/marine-accident-integrated-analysis-system-using-highly-advanced-m-s-system-of-fsi-analysis-technique

https://www.dynalook.com/conferences/european-conf-2007/fe-modelling-of-hydrodynamic-hull-water-impact.pdf/view

https://www.dynalook.com/conferences/international-conf-2010/Simulation-5-1.pdf/view

 

Also, these ICFD examples might be useful:

https://www.dynaexamples.com/icfd

 

Let me know how it goes.

 

Reno.

[Abhemanyu Palaniswamy Chandrasekaran]

Dear Reno,

Thank you very much for the reference papers.

I am interested in the added mass forces arising before the collision event and its effects on the fluid-structure interaction model. Boundary layer and drag effects can be neglected. 

I found this following guideline document from the LS-DYNA aerospace working group.(https://awg.ansys.com/MGD). In page 75 it is mentioned that the ALE solver is not well suited for longer duration problems. I would like to know if this is regarding the numerical stability of the solutions.

Regards

Abhemanyu

[Aspen Webster]

The Arbitrary Lagrangian-Eulerian (ALE) method can be suitable for simulations involving larger time durations, as it allows for the mesh to move and deform with battleship game the flow. This can be advantageous for capturing complex fluid-structure interactions over extended periods. However, the choice of method depends on various factors, including the specific problem, computational resources, and desired accuracy. It is recommended to perform a feasibility study and consider the trade-offs between accuracy and computational cost before selecting the ALE method for your simulation.

[Abhemanyu Palaniswamy Chandrasekaran]

Dear Aspen,

Thank you for the insight. I am currently trying to model the wake around a partially submerged cylinder so as to get an idea of the modelling parameters such as the coupling penalty which I can then use to continue my actual collision simulation. This would also give me an idea of the computational efforts required in my actual simulation.

Regards

Abhemanyu