MPS方法数值模拟楔形体入水问题

Numerical simulation of water entry for two-dimensional wedge by MPS

入水问题是船舶海洋工程中典型的流动问题。当船舶在恶劣海况中航行或海洋平台遭遇恶劣天气时,结构物和水体之间往往会出现剧烈的砰击作用。砰击发生时,伴随着结构物湿表面的变化、自由液面的翻卷和破碎等强非线性现象。本文采用本课题组自主开发的基于移动粒子半隐式法MPS(Moving Particle Semi-Implicit Method)的求解器MLParticle-SJTU对二维楔形体入水问题进行了数值模拟。选取斜升角为30°的楔形体模拟其入水过程,研究了不同粒子布置方式对于计算结果如垂向水动力和自由面变化的影响,并与MLM砰击模型(Modified Logvinovich Model)的结果进行了比较,吻合较好。在此基础上,进一步研究了不同斜升角对计算结果(垂向水动力和自由面变化)的影响,其中流动分离前的垂向水动力与MLM结果相近,表明了MPS方法能有效地模拟入水问题。

Water impact has been a typical problem in ocean engineering.When a vessel sails in the ocean under serious conditions,slamming impact between the structure and water can be huge.The phenomena such as the drastic change of wetted region and the fragmentation and overturning of free surface will happen with the slamming.In this paper,an in-house mesh-free particle solver MLParticle-SJTU,which is developed based on improved moving particle semi-implicit(MPS)method,is employed to numerically simulate the water entry of a two-dimensional(2-D)wedge.The water entry of wedge model with its deadrise angle of 30°is simulated.The effects of two different layout method of particles on vertical force and deformation of free surface are investigated.And the results of MPS are in a good agreement with the results of MLM(Modified Logvinovich Model).In addition,the wedges with different deadrise angles is modeled to study its effects on vertical force and free surface.The agreement of vertical force before flow separation between MPS and MLM is very good which proves the validity of MPS in the research of water entry problems.