Rapid characterisation and modelling of marine biofilm deformation for estimating biofouling frictional drag

海运每年排放约9.4亿吨二氧化碳。船舶经常被海洋生物膜污染，导致摩擦阻力和燃料损失增加，这些损失从轻微到非常昂贵（约18%的动力损失）不等，并且大大增加了全球温室气体排放。污垢生物膜在微生物组成、结构和覆盖率方面是多样的。通过涂料开发和船体维护实现有效的污垢管理是全球船舶船体涂料行业的重要目标，并将为船舶脱碳做出重大贡献。虽然生物膜明显增加了船体表面粗糙度，但其阻力影响不能仅用粗糙度来解释。相反，生物膜的机械性能，物理性能，表面积覆盖率和它们的相互作用被假设为是重要的污垢摩擦阻力的塑造者。生物膜是粘弹性材料，当受到物理应力时，其在一定程度上变形，从而耗散可能使聚合物基质破裂从而导致分离的能量。然而，超过正常条件的流体动力应力可导致生物膜侵蚀和脱离，改变污染表面及其产生的阻力特性。生物膜基质的机械性质响应于流动条件。在全球航运船队中存在的船舶活动概况的范围内，结垢生物膜可以具有显著不同的机械特性，并且当船舶移动通过水中时，它们对通过剪切的流体动力学清除的敏感性可以说将类似地变化。 生物膜机械和物理指标，可预测不同流体动力学条件下的生物膜阻力。然而，关键的挑战是，一个强大的预测建模和测试技术的生物膜机械性能目前还没有。在这个项目中，我们的目标是开发预测生物膜测试和建模技术集中在生物力学和流体动力学阻力。这可能会对船体摩擦阻力和全球海洋温室气体排放产生重大影响。

Maritime transport emits around 940 million tonnes of CO2 annually. Ships are often fouled by marine biofilms, resulting in increased frictional drag and fuel penalties that can range from minor to very costly (~18% powering penalty), and which contribute significantly to global greenhouse gas emissions. Fouling biofilms are diverse in microbial composition, structure, and coverage. Effective fouling management through coating development and hull maintenance are essential targets for the global ship hull coatings industry and will make significant contributions to marine decarbonisation. While biofilms demonstrably increase hull surface roughness, their drag impact cannot be explained by roughness alone. Rather, biofilm mechanical properties, physical properties, surface area coverage and their interplay are hypothesised to be important shapers of fouling frictional drag. Biofilms are viscoelastic materials which deform to some degree when physically stressed, dissipating energy that might otherwise rupture the polymer matrix resulting in detachment. Hydrodynamic stress beyond normal conditions, however, can result in biofilm erosion and detachment, altering a fouled surface and its resulting drag properties. The mechanical properties of a biofilm matrix are responsive to flow conditions. Across the range of vessel activity profiles present in the global shipping fleet, fouling biofilms can have significantly different mechanical properties, and their susceptibility to hydrodynamic clearance through shearing as the vessel moves through the water arguably would similarly vary. Biofilm mechanical and physical metrics that are predictive of biofilm drag across different hydrodynamic conditions. However, the key challenge is that a robust predictive modelling and testing techniques for biofilm mechanical properties are currently not available. In this project, we aim to develop predictive biofilm testing and modelling techniques centred on biomechanics and hydrodynamic drag. This can potentially make a significant contribution to hull frictional drag and global maritime greenhouse gas emissions.