FROTH: Fundamentals and Reliability of Offshore Structure Hydrodynamics

泡沫项目是五所大学之间的密切合作，这些大学在波浪与固定和浮动结构相互作用的研究方面拥有丰富的经验，共同努力将他们的专业知识结合并应用于问题的不同方面。其目的是通过一个精心整合的大规模数值模拟和物理实验方案，研究刚性和弹性结构上的剧烈水动力冲击载荷的详细物理学。将开发开放源码数值代码来模拟将在Uop[http://www.plymouth.ac.uk/pages/view.asp?page=34369].的新的National Wave和Current设施中进行的实验室实验众所周知，气候变化将导致英国和欧洲西北部近海海洋环境中海平面上升和风暴活动增加(要么是更严重的个别风暴，要么是更多的风暴，或者两者兼而有之)。这对现有近海结构物上人员的安全以及现有和新型液化天然气运输船的安全运营具有重大影响，这些运输船的结构由于在恶劣的海面上剧烈晃动运输的液体而承受着巨大的瞬时载荷。英国水域现有的一些石油和天然气近海结构已经有40年的历史，这些老化的结构需要重新评估，以确保它们能够承受由于气候变化而增加的载荷，并确认它们的寿命可以延长到未来25年。升级这些现有结构以及确保新结构和船舶的生存能力和安全运行的费用将严重取决于水动力冲击载荷预测的可靠性。这些载荷会对海堤、为液体晃动提供容器的储罐(如LNG运输船)造成严重破坏，并对浮式生产储油船和其他海上浮动结构物(如波能转换器)造成损害。虽然对流体主体中的流体动力学相对较好，但水面的剧烈运动和破裂仍然是以足够精度模拟工程设计的主要挑战。虽然分析技术通常能相对较好地预测自由面高度和平均载荷，但在这种极端条件下，观测到的瞬时峰值压力并不能可靠地预测，即使在严格控制的实验室实验中，也往往无法重复。关于流体动力冲击载荷的详细物理问题，即使对于固定结构和可能发生的极高压力脉冲，仍然存在一些深层次的基本悬而未决的问题。特别是，在对下列影响的理解方面存在不确定性：由于水的声学性质的变化导致在实验中测量的波浪冲击压力的可变性；结构的灵活性导致水弹性响应；入射波的陡度和三维性。本提案试图通过一套紧密结合的实验室实验和最新的数值模拟直接解决这一根本困难和安全关键的问题，最终目的是为近海、海洋和沿海结构物的设计者提供更好的指导，无论是固定的还是浮动的。

The FROTH project is a close collaboration between five universities with significant experience in research into wave interactions with fixed and floating structures working together to combine and apply their expertise to different aspects of the problem. The aim is to investigate the detailed physics of violent hydrodynamic impact loading on rigid and elastic structures through a carefully integrated programme of numerical modelling and physical experiments at large scale. Open source numerical code will be developed to simulate laboratory experiments to be carried out in the new national wave and current facility at the UoP [http://www.plymouth.ac.uk/pages/view.asp?page=34369]. It is well known that climate change will lead to sea level rise and increased storm activity (either more severe individual storms or more storms overall, or both) in the offshore marine environment around the UK and north-western Europe. This has critical implications for the safety of personnel on existing offshore structures and for the safe operation of existing and new classes of LNG carrier vessels whose structures are subject to large instantaneous loadings due to violent sloshing of transported liquids in severe seas. Some existing oil and gas offshore structures in UK waters are already up to 40 years old and these aging structures need to be re-assessed to ensure that they can withstand increased loading due to climate change, and to confirm that their life can be extended into the next 25 years. The cost of upgrading these existing structures and of ensuring the survivability and safe operation of new structures and vessels will depend critically on the reliability of hydrodynamic impact load predictions. These loadings cause severe damage to sea walls, tanks providing containment to sloshing liquids (such as in LNG carriers) and damage to FPSOs and other offshore marine floating structures such as wave energy converters.Whilst the hydrodynamics in the bulk of a fluid is relatively well understood, the violent motion and break-up of the water surface remains a major challenge to simulate with sufficient accuracy for engineering design. Although free surface elevations and average loadings are often predicted relatively well by analysis techniques, observed instantaneous peak pressures are not reliably predicted in such extreme conditions and are often not repeatable even in carefully controlled laboratory experiments. There remain a number of deeply fundamental open questions as to the detailed physics of hydrodynamic impact loading, even for fixed structures and the extremely high-pressure impulse that may occur. In particular, uncertainty exists in the understanding of the influence of: the presence of air in the water (both entrapped pockets and entrained bubbles) as the acoustic properties of the water change leading to variability of wave impact pressures measured in experiments; flexibility of the structure leading to hydroelastic response; steepness and three dimensionality of the incident wave.This proposal seeks to directly attack this fundamentally difficult and safety-critical problem with a tightly integrated set of laboratory experiments and state of the art numerical simulations with the ultimate aim of providing improved guidance to the designers of offshore, marine and coastal structures, both fixed and floating.