Reporter:Xiaobo Chen, Director of International R&D Cooperation, Research Department, Bureau Veritas Marine & Offshore, France

Report topic:Challenges of ship seakeeping in waves and one solution using free-surface Green function

Report time: 10:30-12:00,17th November, 2023 (Friday)

Report location: Conference Room 315, Ship Marine Building (offline)

Brief introduction of the reporter

Dr. Xiaobo Chen is a research scientist, a graduate of the Tsinghua University (China) awarded in 1983 as a distinguished graduating student. In 1988, he got his Ph.D. in Hydrodynamics of Ecole Centrale Nantes (France). After the post-doctoral fellowship in Institute Français du Pétrole, he joined Bureau Veritas in 1991. He has worked in the Research Department of the Marine Division, then the Head of Hydrodynamics & Mooring Section. He has been member of the IACS working group WD-SL and the ISSC Technical Committee on Loads, and the chairman of recent IACS-HPT01 working on the harmonization of Common Structure Rules.

Report summary

We present our R&D on ship seakeeping problem using the fundamental solution including wavy properties and viscus effects. Within the theoretical framework, the ship-shaped stream (often called double-body flow) is chosen as the base flow over which is superposed the perturbation flow composed of a wavy steady flow and an unsteady flow. The boundary conditions on the free surface satisfied by the steady and unsteady potentials are then formulated. A set of boundary integral equations (BIE) is established by applying the Green theorem. The resultant BIE includes the classical integral on the ship hull, a localized free-surface integral in the vicinity of ship and extra integral equations imposed over the waterplane inside the ship hull to guarantee that the whole system is well-conditioned to yield stable and convergent solutions. The Green function associated with a pulsating and translating source is reformulated by considering the viscous effect so that the singular and highly oscillatory behaviours disappear naturally. The integration of Green’s function over flat panels is evaluated accurately by making use of analytical formulations. Furthermore, a new and consistent decomposition of radiation forces is developed by considering the speed-effect stiffness due to the steady flow. Together with recent enhancements including the treatment of both lower-order (flat panels) and higher-order meshes (quadratic curved patches), this solution method for ship seakeeping with forward speed has been shown to be reliable and practical in the application for ship design.

host unit:

School of Shipbuilding Engineering, Harbin Engineering University

organizer:

The National International Joint Research Center for Marine Engineering and Marine Engineering Mechanics of the Ministry of Science and Technology

The Belt and Road Joint Laboratory of Polar Technology and Equipment of the Ministry of Science and Technology

Key Laboratory of Polar Equipment and Technology, Ministry of Industry and Information Technology

Joint Laboratory of International Cooperation between Ship and Marine Engineering Technology of the Ministry of Education

Talent and Education Committee of China Shipbuilding and Engineering Society

Heilongjiang Provincial Shipbuilding and Engineering Society