Department of Environmental Sciences, University of Virginia, Charlottesville, USA.
Department of Mechanical Engineering, United States Naval Academy, Annapolis, Maryland, USA.
Biofouling. 2022 Aug;38(7):696-714. doi: 10.1080/08927014.2022.2117033. Epub 2022 Sep 5.
Algal biofilms, ubiquitous in aquatic systems, reduce the performance of engineered systems and alter ecosystem processes. Biofilm morphology is dynamic throughout community development, with patchiness occurring due to periodic sloughing, but little is known about how community level physical structure affects hydrodynamics. This study uses high resolution particle image velocimetry (PIV) to examine spatially explicit turbulence over sparse, uniform and patchy biofilm at turbulent Reynolds numbers. All biofilms increase the near-bed turbulence production, Reynolds shear stress, and rotational flow compared to a smooth wall, and non-uniform biofilms have the greatest increase in these parameters, compared with a uniform or sparse biofilm. However, a higher drag coefficient over uniform biofilm compared with non-uniform biofilm indicates that percent coverage (the amount of area covered by the biofilm) is a useful predictor of a biofilm's relative effect on the total drag along surfaces, and in particular the effect on ship performance.
藻类生物膜在水生系统中无处不在，降低了工程系统的性能并改变了生态系统过程。生物膜形态在整个群落发展过程中是动态的，由于周期性的剥落而出现斑块状，但对于群落水平的物理结构如何影响水动力知之甚少。本研究使用高分辨率粒子图像测速 (PIV) 在湍流雷诺数下研究稀疏、均匀和斑块状生物膜的空间显式湍流。与光滑壁相比，所有生物膜都增加了近床湍流生成、雷诺切应力和旋转流，与均匀或稀疏生物膜相比，非均匀生物膜对这些参数的增加最大。然而，与非均匀生物膜相比，均匀生物膜的阻力系数更高，这表明覆盖率（生物膜覆盖的面积百分比）是生物膜对表面总阻力相对影响的有用预测指标，特别是对船舶性能的影响。
