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MULTI-SCALE TWO-PHASE WAVE-STRUCTURE INTERACTION USING ADAPTIVE SPH COUPLED WITH QALE-FEM

使用自适应 SPH 与 QALE-FEM 耦合的多尺度两相波结构相互作用

基本信息

批准号：
EP/L014890/1
负责人：
Benedict Rogers
金额：
$ 43.08万
依托单位：
University of Manchester
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FL014890%2F1
关键词：
MULTI SCALE TWO PHASE WAVE

项目摘要

Considerable advances have been made in the modelling of wave hydrodynamics and wave-body interaction in recent years. Wave diffraction analysis based on potential flow theory is now standard with linear and second-order theory in the frequency domain. In the time domain for fully nonlinear analysis arguably the most versatile, robust and efficient method is the arbitrary Lagrange-Euler finite-element method (QALE-FEM) approach for potential flow, capable of covering 3-D domains of say 20x20 wavelengths in plan with 20 wave periods on overnight runs on an 8-core processor. However, the method is single-phase with the physical limitation of an irrotational, inviscid fluid. Extreme loads and impacts or slam generally involve breaking wave conditions where multi-phase (air-water-solid) behaviour is significant. An alternative approach is required for violent flows with complex physics local to a structure or body. Progress with volume-of-fluid (VOF) methods has been applied to wave interactions with columns and coastal structures. However, the most significant advances for violent wave-structure have recently been made using the Smoothed Particle Hydrodynamics (SPH) method. SPH has been an area of promising research for some years due to its versatility in dealing with free-surface flows with overturning, splashing and body interaction. Recent problems with numerical convergence, stability and very noisy pressure have been resolved for single-phase flow through EPSRC funded work through an incompressible, divergence-free, formulation (ISPH). Numerical convergence with high pressure accuracy for several impulsive test cases has been demonstrated with generalised shifting algorithms for eliminating instabilities within the particle distributions. Clearly, predicting high pressure accurately is vital for fluid-body interaction. This has been extended to two-phase flow with the incorporation of a compressible air phase with good results in preliminary tests. The main disadvantage of SPH is the computational time due to the large number of particles required in 3-D, O(10 million - 1 billion), the large number of neighbour interactions per particle, and the relatively small time steps needed. Variable particle sizing and efficient neighbour searching do not enable domain dimensions of many wavelengths in 3-D to be run for many wave periods as generally required for extreme wave-body interaction. Building on previous work, in this project ISPH and QALE-FEM for wave-structure interaction will be developed in parallel and then coupled achieving efficient computation in two ways:1. Dynamic adaptive particle sizing, satisfying minimum error conditions or resolving some physical characteristic, e.g. density or vorticity. Promising preliminary results have been obtained in 2-D by the proposers.2. Coupling an inner SPH domain with an outer nonlinear potential flow domain using an efficient solution method such as QALE-FEM. Dynamic adaptive particle sizing should also be used in the SPH domain.

近年来，在波浪流体力学和波体相互作用的模拟方面取得了长足的进展。基于势流理论的波浪绕射分析现在是标准的频域线性和二阶理论。在完全非线性分析的时间域中，最通用、最稳健和最有效的方法是势流的任意拉格朗日-欧拉有限元方法(QALE-FEM)，该方法能够在8核处理器上过夜运行，覆盖计划中的三维区域，例如20×20个波长和20个波周期。然而，该方法是单相的，具有无旋转、无粘性流体的物理限制。极端载荷和冲击或猛烈撞击通常涉及破坏波浪条件，其中多相(空气-水-固体)行为显著。对于结构或身体局部具有复杂物理特性的剧烈流动，需要另一种方法。流体体积(VOF)方法的进展已应用于波浪与柱子和海岸结构物的相互作用。然而，最近利用光滑粒子流体动力学(SPH)方法对剧烈波浪结构的研究取得了最显著的进展。多年来，SPH一直是一个有前途的研究领域，因为它在处理具有倾覆、飞溅和身体相互作用的自由表面流动方面具有多功能性。通过一种不可压缩、无发散的公式(ISPH)，单相流通过EPSRC资助的工作解决了最近的数值收敛、稳定性和非常嘈杂的压力问题。用广义移位算法消除了颗粒分布中的不稳定性，证明了几个脉冲试验算例具有高压力精度的数值收敛。显然，准确预测高压对于流体-物体相互作用至关重要。这已扩展到两相流，加入了可压缩空气相，在初步试验中取得了良好的结果。SPH的主要缺点是在3-D，O(1000万-10亿)中需要大量的粒子，每个粒子需要大量的邻域相互作用，并且所需的时间步长相对较小，因此计算时间较长。可变的粒子大小和有效的邻域搜索不能像极端的波体相互作用通常所要求的那样，在3-D中使许多波长的域维度运行许多波周期。在前人工作的基础上，本文将波-结构相互作用的ISPH和QALE-有限元并行发展，然后耦合起来，通过两种方式实现有效的计算：1.动态自适应颗粒尺寸，满足最小误差条件或解决某些物理特性，如密度或涡度。这些提出者已经在2-D中获得了有希望的初步结果。使用一种有效的求解方法，如QALE-FEM，将内SPH区域与外部非线性势流区域耦合。在SPH领域中也应该使用动态自适应颗粒大小。