Development of rational design methodology of deep sea riser

我们完成了一个计算机代码来数值模拟深海立管的行为。对规范进行了有限差分和有限元建模研究；后者被雇用了。立管本体分为许多段。局部弯曲和扭转由相邻段的相对位移表示，相邻段假定为刚性。然而，每个节被认为是延伸和压缩响应张力和压缩。从用欧拉角表示的系统的拉格朗日函数出发，导出了由各节段组成的系统的运动方程。假设相对流动发生在与管片圆柱体轴线垂直的平面上，并且没有分量进入轴线，则计算管片上的水动力、附加质量和阻力。通过将模拟的运动、拉力和弯矩与实验结果进行比较，验证了计算机程序的正确性。实验采用立管悬垂条件和支撑平台在波浪中漂浮时的强迫运动。我们用自己开发的计算机代码设计了一个深海立管。

We completed a computer code to numerically simulate the behaviors of deep sea riser.Both finite difference and finite element modeling have been studied for the code ; the latter was employed. Riser body is divided into numerous segments. Local bending and torsion are represented by the relative displacement of neighboring segments which are assumed rigid. Nevertheless each segment is assumed to extend and compress responding to tension and compression.We derive the equation of motion of a system of the segments from Lagrangean function of a system written in the Euler angle of each segment. Hydrodynamic forces on the segments, added mass and drag force, are computed assuming that the relative flow occurs in the plane normal to the axis of the segment cylinder and has no component into the axis.Our computer code was validated by comparing the simulated motion, tension and bending moment, with the measured ones obtained in the experiments. The experiment are with the hang-off condition of a riser and the forced motion given by the supporting platform floating in waves.We designed a deep sea riser by using the computer code we developed.