Evaluation of Hydrodynamic Drag on Experimental Fouling-release Surfaces, using Rotating Disks

Abstract

Fouling by biofilms significantly increases frictional drag on ships' hulls. A device, the friction disk machine, designed to measure torque on rotating disks, was used to examine differences among experimental fouling-release coatings in the drag penalty due to accumulated biofilms. Penalties were measured as the percentage change in the frictional resistance coefficient Cf. Drag penalties due to microfouling ranged from 9% to 29%, comparable to previously reported values. An antifouling control coating showed a smaller drag penalty than the fouling-release coatings. There were also significant differences among the fouling-release coatings in drag due to biofilm formation. These results indicate that the friction disk machine may serve as a valuable tool for investigating the effects of experimental coatings, both antifouling and fouling-release, on microfouling and associated drag penalties.

Effects of biofouling development on drag forces of hull coatings for ocean-going ships: a review

“…75 For instance, Aldred et al 76 stated that cyprids not only actively choose to settle on surfaces with the maximum number of attachment points, but it also increased the attachment strength. Theoretically, therefore, rougher coating surfaces are more likely to be biofouled than smooth surfaces, 43 and their biofouling release requires higher traveling speeds compared to smoother surfaces. The least preferred topographies with the lowest number of attachment points offer a diminished settlement and growth of the propagules and larvae of fouling organisms 77 ; in addition, they favor the release of biofouling from surfaces.…”

“…6). 43 As depicted in Fig. 7, along the disk surface, three regions can be distinguished: a laminar flow region, a transient region, and a turbulent flow region.…”

“…The friction disk machine (FDM) has been used by several authors to measure the drag induced by surfaces [e.g., references (41)(42)(43)(44)]. Granville used rotating disks to determine the skin friction coefficient of rough surfaces.…”

“…The FDM used by Holm et al employed disks of 22.86 cm in diameter and 0.3 cm in thickness. 43 The disks were immersed in a cylindrical test chamber of 25 cm in height and 33 cm in diameter. The disks were then spun from 700 to 1500 RPM, with changes of 200 RPM.…”

Temperature Affects Adhesion of the Acorn Barnacle (Balanus amphitrite)

“…Recruitment of marine organisms is a natural and important aspect of intertidal systems, yet it can be problematic when it occurs on man-made substrata. Biofouling accumulation results in major ecological and economic costs when the substrate becomes corroded, blocked or damaged while in use (Callow and Callow 2002;Schultz et al 2003;Holm et al 2004a). Biofouling is also an important vector of invasive species (Brancato and Maclellan 1999;Godwin et al 2004;Mineur et al 2008;Piola and Johnston 2008;Piola et al 2009).…”