Roughness effects of diatomaceous slime fouling on turbulent boundary layer hydrodynamics. Issue 9 (21st October 2018)

• Record Type: Journal Article
• Authors: Murphy, Elizabeth A. K.; Barros, Julio M.; Schultz, Michael P.; Flack, Karen A.; Steppe, Cecily N.; Reidenbach, Matthew A.
• Is Part Of: Biofouling. Volume 34:Issue 9(2018)
• Page Start: 976
• Page End: 988
• Publication Date: 2018-10-21
• Subjects: Biofilm -- turbulence -- drag -- roughness -- PIV -- boundary layer; Marine fouling organisms -- Periodicals; Materials -- Biodeterioration -- Periodicals; Fouling -- Periodicals; Biodegradation -- Periodicals; Environmental Microbiology -- Periodicals; Water Microbiology -- Periodicals; 576.165
• DOI: 10.1080/08927014.2018.1517867
• Languages: English
• ISSNs: 0892-7014

Abstract

Abstract: Biofilm fouling significantly impacts ship performance. Here, the impact of biofilm on boundary layer structure at a ship-relevant, low Reynolds number was investigated. Boundary layer measurements were performed over slime-fouled plates using high resolution particle image velocimetry (PIV). The velocity profile over the biofilm showed a downward shift in the log-law region ( ΔU + ), resulting in an effective roughness height ( ks ) of 8.8 mm, significantly larger than the physical thickness of the biofilm (1.7 ± 0.5 mm) and generating more than three times as much frictional drag as the smooth-wall. The skin-friction coefficient, Cf, of the biofilm was 9.0 × 10 −3 compared with 2.9 × 10 −3 for the smooth wall. The biofilm also enhances turbulent kinetic energy ( tke ) and Reynolds shear stress, which are more heterogeneous in the streamwise direction than smooth-wall flows. This suggests that biofilms increase drag due to high levels of momentum transport, likely resulting from protruding streamers and surface compliance.