Drag production mechanisms of filamentous biofilms |
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| Authors: | Joel D. Hartenberger James W. Gose Marc Perlin Steven L. Ceccio |
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| Affiliation: | 1. Department of Naval Architecture and Marine Engineering, University of Michigan, Ann Arbor, MI, USA;2. Department of Naval Architecture and Marine Engineering, University of Michigan, Ann Arbor, MI, USA;3. Department of Ocean Engineering, Texas A&4. M University, College Station, TX, USA |
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| Abstract: | Abstract Biofilms were grown on smooth acrylic surfaces for nominal incubation times of three, five, and ten weeks in a flow loop at the University of Michigan. The biofilm covered surfaces were exposed to the turbulent flow in a high-aspect ratio, fully developed channel flow facility at height-based Reynolds numbers from ReH ≈ 5,000 to 30,000. Measurements of the pressure drop along each fouled upper surface revealed that the friction drag increased from approximately 10% to 400%. The wide range in drag penalty was linked to variations in flow speed, the average thickness of the biofilms, and the level of film coverage over each surface through scaling parameters and empirical correlations. Rigid replicas of select biofilms were produced from time-averaged laser scans collected while the biofilm was subjected to flow. These rigid biofilm replicas experienced roughly half the drag increase of their compliant counterparts with the increase in friction spanning roughly 50% to 200%. |
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| Keywords: | Biofilm drag turbulence fully developed flow roughness compliance |
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