Session: 08-01-03 Ship Design and Surface Wave Effects I

Paper Number: 127678

127678 - Fluid Structure Interactions for Ship Advancing in Waves With Constant Forward Speed 

Evaluation of the structural stresses for the ships, advancing with constant speed  in waves, represents a very important practical problem. The main technical difficulty comes from the solution of the hydrodynamic seakeeping problem which, in the case of ship advancing with constant speed is incomparably more complicated than the problem of stationary vessel ( U = 0). This is mainly due to the complexity of the associated free surface condition.

In the present work the linearized seakeeping problem at forward speed is solved under the assumptions of potential flow and using the Boundary Integral Equation Method based on the Kelvin type of Green’s function. The details of the hydrodynamic solution were presented in Chen X.B. et al. 2022 and here we concentrate on the coupling with the structural 3D FE model. For the time being, the quasi-static hydro-structure interactions are of concern only so that the main technical issue becomes the transfer of the hydrodynamic pressure from the hydrodynamic Boundary Element mesh to the structural Finite Element mesh. In the case of the stationary vessels, thanks to relative simplicity of the associated Green’s function, it was possible to easily recalculate the hydrodynamic pressure, at any point in the fluid after solving the Boundary Integral Equations (Malenica et al. 2009). In this way the coupling procedure was highly simplified and the potential problems of interpolation of the pressure from one mesh to another, were avoided since the pressure was directly calculated at the Gauss points of the finite elements. In the case with U > 0 the equivalent procedure is not practically possible, and the interpolation procedure is required. Within the interpolation procedurwetch is adopted here, the advantage is taken from the fact that the higher order panels are used to solve the hydrodynamic problem, so that the pressure has continuous distribution over the wetted part of the body. This allows for consistent interpolation of the pressure across each panel. One of the critical technical points, which occurs within the procedure, is the local parametrization of each Gauss point. For that purpose, various searching strategies are implemented and tested such as: "SLSQP" (sequential least squares programming algorithm), "TNC" (truncated Newton method), "BFGS" (Broyden–Fletcher–Goldfarb–Shanno algorithm), "Powell", "nelder-mead". Accuracy and robustness of each algorithm are discussed and the results from application to a real ship are also presented.

References

Chen X. B., Nguyen M. Q., Ten I., Housseine C. O., Choi Y. M., Diebold L., De Hauteclocque G., Derbanne Q. (2022). New seakeeping computations based on Potential flows linearised over the ship-shaped stream. PRADS.

Malenica S., Sireta F. X., Bigot F., Wang C., & Chen X. B. (2009). Some Aspects of Hydro-Structure Coupling for Combined Action of Seakeeping and Sloshing. OMAE.

Presenting Author: Minh Quan Nguyen Bureau Veritas

Presenting Author Biography: Nguyen Minh Quan is a research engineer who works in Research Department of Bureau Veritas since 2021. He got his mechanical engineering degree in 2012 from INSA Lyon and his PhD in fluid mechanics from Ecole Central Lyon in 2016.

Authors:

Minh Quan Nguyen Bureau Veritas
Guillaume De Hauteclocque Bureau Veritas
Jerome De Lauzon Bureau Veritas
Sime Malenica Bureau Veritas
Xiaobo Chen Bureau Veritas