A 3D multi-domain high order boundary element method to evaluate time domain motions and added resistance of ship in waves. (1st July 2018)

• Record Type: Journal Article
• Authors: Chen, Xi; Zhu, Ren-chuan; Zhou, Wen-jun; Zhao, Ji
• Is Part Of: Ocean engineering. Volume 159(2018)
• Page Start: 112
• Page End: 128
• Publication Date: 2018-07-01
• Subjects: Multi-domain HOBEM -- Time domain -- Ship motion -- Forward speed -- Added wave resistance; Ocean engineering -- Periodicals; Ocean engineering; Periodicals; 620.4162
• DOI: 10.1016/j.oceaneng.2018.03.091
• Languages: English
• ISSNs: 0029-8018

Abstract

Abstract: A newly developed three dimensional multi-domain high order boundary element method (MDHOBEM) is applied to solve time domain ship motions in waves for ships advancing with forward speed, as well as the corresponding added wave resistances. By the method, fluid domain is decomposed by a regular control surface into inner and outer parts, in which Rankine panel method and transient Green function method are adopted respectively. By the MDHOBEM, the problem of highly oscillatory nature of transient Green function near waterline can be avoided due to substitution of Rankine source in inner domain. Fewer discrete quantities than in Rankine panel method is needed as transient Green function is employed in outer domain, and the radiation condition can be analytically satisfied as well. Boundary value problem of velocity potential is solved in a translational and inertial frame without use of moving mesh, implying it is a highly efficient approach. A mixed form of ship wave linearized or double body flow linearized free surface condition, and the according m -terms are employed in inner domain to treat the steady flow effects more accurately. The yielding hybrid boundary integral equations are discretized with bi-quadratic isoparametric high order elements to minimize discretization error. A Fortran code is originally developed, and is used to simulate wave-body interactions of both the wall-sided and flared hulls including mathematical Wigley-3 hull, Series60, and more realistic hull forms of KCS and S175. Convergence of spatial and temporal discretization, and size of inner domain are detailedly investigated beforehand. Results indicate the present numerical scheme has quite good robustness, and the inner free surface can be reduced to a rather small region comparing to Rankine panel method. The computed hydrodynamic coefficients, added wave resistance and ship motions by MDHOBEM are compared with model test data and results of classic boundary element methods including Rankine panel method, transient Green function method, and translating and pulsating Green function method. It manifests the MDHOBEM has quite good accuracy and needs less computational cost. Highlights: We developed a three dimensional multi-domain HOBEM to solve time domain ship motion in waves and added wave resistance. By the MDHOBEM, the problem of highly oscillatory nature of transient Green function near waterline can be avoided. Fewer discrete quantities are needed in MDHOBEM, and the radiation condition can be analytically satisfied. A mixed form of steady ship wave or double body flow linearized free surface condition is employed in inner domain. We also analyzed different physical components of added wave resistance by using near field integrals.