Modeling the flow regime near the source in underwater gas releases

Recent progress in calculating gas bubble sizes in a plume, based on phenomenological approaches using the release conditions is a significant improvement to make the gas plume models self-reliant. Such calculations require details of conditions Near the Source of Plume (NSP); (i.e. the plume/jet velocity and radius near the source), which inspired the present work. Determining NSP conditions for gas plumes are far more complex than that for oil plumes due to the substantial density difference between gas and water. To calculate NSP conditions, modeling the early stage of the plume is important. A novel method of modeling the early stage of an underwater gas release is presented here. Major impact of the present work is to define the correct NSP conditions for underwater gas releases, which is not possible with available methods as those techniques are not based on the physics of flow region near the source of the plume/jet. We introduce super Gaussian profiles to model the density and velocity variations of the early stages of plume, coupled with the laws of fluid mechanics to define profile parameters. This new approach, models the velocity profile variation from near uniform, across the section at the release point to Gaussian some distance away. The comparisons show that experimental data agrees well with the computations.     

峡谷河流的挂网式人行悬索桥设计

为了降低峡谷河流人行悬索桥的造价,本文提出一种峡谷河流的双曲抛物面空间缆索挂网式人行悬索桥,将双曲抛物面空间缆索网分散锚固于峡谷河流两侧的悬崖陡壁岩石之上,取消桥塔,取消吊索体系,管桁架式桥面加劲梁直接搁置在双曲抛物面空间缆索网之上,节约造价,装配式施工简便。结合某150m跨径峡谷河流人行景观悬索桥,建立Midas有限元分析模型,开展动力模态特性分析研究,验证了双曲抛物面空间缆索挂网式人行悬索桥结构具有良好的抗风稳定性。