Time domain simulation of SeaFEM

==Abstract==

There are a series of marine operations and/or navigation conditions where internal flows in tanks can affect the seakeeping behaviour of a vessel. This coupled effect must be assessed as it can be extremely important when estimating the viability of certain operations or the risks associated to specific load conditions during navigation. These operations and/or navigation conditions can be crucial in some sectors of the maritime industry where fluid-dynamic effects can improve the global dynamic response, such as anti-roll tanks used in the oil&gas industry, or can prove to be a big problem when, for example, sloshing effects appears in the transport of Liquefied Natural Gas (LNG).
This presentation has two main parts. First, the recent work of the MARINE group of CIMNE in the development and application of seakeeping analysis tools will be presented. Here, we will introduce SeaFEM (see http://www.compassis.com/seafem), a second-order diffraction-radiation solver for multi-body seakeeping problems based on the Finite Element Method [1, 2]. Then, we will focus on the development and application of solutions for the coupled analysis of seakeeping problems considering internal flows in tanks, and in particular the sloshing phenomena. To estimate these critical effects, two different solvers are integrated into one coupled tool using an effective coupling algorithm and a communication technique that allows simulations to be computed without affecting the global compute time and the accuracy of the solvers. Two different approaches have been implemented and validated:
a) The internal flow part of the coupled problem is solved using the Smoothed Particle Hydrodynamics Method [3] (SPH) using the AQUAgpusph code developed at CEHINAV. While the interaction between waves and the floating body is solved using SeaFEM.
b) The fluid dynamics part of the coupled problem is solved using the Particle Finite Element Method [4, 5] known as PFEM-2 that incorporates the X-IVAS scheme and the seakeeping problem is again solved using SeaFEM.

==PRESENTATION==

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==References==


[1] Serván-Camas, B., García-Espinosa, J. “Accelerated 3D multi-body seakeeping simulations using unstructured finite elements”. Journal of Computational Physics, vol. 252, pp. 382-403, Nov. 2013.

[2] Serván-Camas, B., “A time-domain finite element method for seakeeping and wave resistance problems”. PhD thesis. Universidad Politécnica de Madrid (2016).

[3] B. Servan Camas, J. Cercós-Pita, J. Colom Cobb, J. García-Espinosa and A. Souto-Iglesias, "Time domain simulation of coupled sloshing–seakeeping problems by SPH–FEM coupling", Ocean Engineering, 123, (2016), 383–396. URL: www.scipedia.com/public/Servan_Camas_et_al__2016a

[4] Idelsohn, S.R., Oñate, E. Del Pin, F. “The particle finite element method: a powerful tool to solve incompressible flows with free‐surfaces and breaking waves”. International journal for numerical methods in engineering, vol. 61-7, pp. 964-989, Oct. 2004.

[5] Idelsohn, S.R., Nigro, N., Limache, A., Oñate, E. “Large time-step explicit integration method for solving problems with dominant convection”. Computer Methods in Applied Mechanics and Engineering, vol. 217–220, pp. 168–185, Apr. 2012.