Experimental and Numerical Investigation of Local Scour Around Submarine Piggyback Pipeline Under Steady Current

As a new type of submarine pipeline, the piggyback pipeline has been gradually adopted in engineering practice to enhance the performance and safety of submarine pipelines. However, limited simulation work and few experimental studies have been published on the scour around the piggyback pipeline under steady current. This study numerically and experimentally investigates the local scour of the piggyback pipe under steady current. The influence of prominent factors such as pipe diameter, inflow Reynolds number, and gap between the main and small pipes, on the maximum scour depth have been examined and discussed in detail. Furthermore, one formula to predict the maximum scour depth under the piggyback pipeline has been derived based on the theoretical analysis of scour equilibrium. The feasibility of the proposed formula has been effectively calibrated by both experimental data and numerical results. The findings drawn from this study are instructive in the future design and application of the piggyback pipeline.     

Numerical Modeling of the Dynamic Response of an Elastoplastic Seabed Under Wave-Current Interactions

Wave-induced liquefaction of the seabed is a geohazard frequently encountered in shallow waters. Although widely discussed, most studies paid attention to the seabed response under a single sequence of wave loading. However, the seabed suffers from repeated ‘wave loading–dissipation’ phases in a real ocean environment. In this study, a homogeneous sandy seabed model is established to investigate the mechanism of wave-induced liquefaction by considering the existence of currents. Finite element a...     

高精度曲面建模最佳表达形式的数值实验分析

高精度曲面建模的发展过程在理论上可归结为对高斯方程组中单个方程不同组合的数值模拟分析比较和检验过程。数值实验分析结果表明,因有限差分所带来的数值困难,高斯方程组中的交叉项方程是影响高精度曲面建模误差和模拟速度的关键因素,高精度曲面建模的最佳数学表达是除交叉项方程之外的其他两个方程的组合。     

大型饼类锻件漏盘镦挤工艺的数值模拟与优化

对带凸台的大型饼类锻件,可采用漏盘镦挤工艺进行生产。针对该工艺,利用ANSYS的APDL语言建立了镦挤过程的参数化有限元模型,采用0阶优化法,对该工艺进行了优化分析,对漏盘结构参数和变形后的坯料尺寸进行了定量分析,为确定漏盘镦挤工艺参数提供了有益的指导。     

海洋标量场时空过程远程动态可视化服务研究

随着多源、大面海洋遥感数据及其反演产品呈指数形式增加,利用网络实现远程长时间序列的海洋标量场动态可视化查询、分析,成为海洋信息服务的迫切需求之一。本文在深入分析现有海量数据网络动态可视化技术及海洋标量场时空变化过程的特点时,针对海洋标量场数据探讨标量场的点过程和面过程的网络可视化表达。并以海表温度数据为例,介绍了从MODIS的海表温度反演产品到网络发布的整个处理流程,构建了中国台海区域海表温度场时空过程的网络可视化原型系统。在该原型系统中,实现了海表温度场任意点位的温度查询,任意点位温度时间变化的过程曲线,温度场面过程时空过程动态演进可视化分析等功能。同时该原型系统可以为其他海洋标量场的时空过程可视化提供技术与方法借鉴。     

基于EEMD高斯过程自回归模型的缝洞型油藏开发动态指标预测

缝洞型油藏储集空间类型多样,大缝大洞的存在使得见水特征复杂多样,同时受各类工程、地质因素影响,生产数据非线性、非稳态,动态指标实时预测难度大。对此提出了一种结合集合经验模态分解(EEMD)和信息熵的高斯过程自回归模型的开发动态指标预测方法:①利用EEMD方法将生产数据分解成若干个平稳的本征模态函数(IMF)分量;②采用信息熵计算由于工作制度频繁调整而引起的数据波动程度;③利用分解的低频分量提取拟稳态数据段,对方差贡献度较大的各IMF分量建立高斯过程自回归模型;④叠加各分量计算结果作为预测值。仿真实验表明这种新算法能够有效应用于缝洞型油藏开发动态指标预测,可以预测生产井各项生产指标的变化趋势,为后期生产开发方案调整提供依据,指导油田的整体开发。