无限区域二维势流直接边界元法精度分析

边界元法作为一种重要的数值方法已在许多领域得到广泛应用,但在船舶水动力势流理论数值计算方面,有关直接边界元法的研究并不充分,尤其是在船舶兴波阻力势流理论求解方面,以往的“面元法”通常是基于Hess-Smith法的间接法,这类方法在理论和数值计算上都存在着缺陷。针对船舶水动力势流理论计算,采用直接边界元法,对二维势流无界绕流算例进行系统的数值计算,并根据二维势流问题的计算结果详细探讨边界单元离散形式和单元上的数值积分方法对计算精度的影响,各项数值计算均以Matlab软件编程实现。结果表明,采用常数单元和龙贝格积分法能够得到较准确的结果,且计算速度较快。

Precision analysis of the two-dimensional potential flow problem in an infinite region with the directboundary element method

The Boundary Element Method (BEM), as a key numerical method, has been widely applied in many fields. However, the research on the Direct Boundary Element Method (DBEM) for ship hydrodynamic numerical calculation problems is still insufficient, especially when it comes to the ship hydrodynamic potential flow theory. The general method-‘panel method’-is based on Hess-Smith method, which is an Indirect Boundary Element Method (IBEM) whose major flaws exist in both theory and numerical calculation. This paper, based on the ship hydrodynamic potential flow theory, adopts DBEM to calculate the example of two-dimensional unbounded potential flow around a cylinder, and analyzes the influence of the boundary element discrete forms and the numerical integral methods on the calculation accuracy. The results carried out by Matlab clearly indicate that using the constant element and Romberg algorithm method could yield high calculation speed and accuracy.