Meeting Abstract
13.4 Monday, Jan. 4 Determination of Lift and Drag Coefficients of Zebra and Quagga Mussels using an Inverse Method HERMANSON, J.C.*; PEYER, S.M.; JOHNSON, J.A.; USFS Forest Products Laboratory; Univ. of Wisconsin-Madison; Univ. of Washington jhermans@wisc.edu
The probability of dislodgment of a mussel in flow depends on the hydrodynamic load it experiences relative to the resistance strength of its byssal threads. Hydrodynamic loading is a function of lift and drag coefficients, which have been determined for mussels, but typically in an artificially attached state. The goal of this study was to use load-resistance factor design (LRFD) analysis to calculate lift and drag coefficients of zebra and quagga mussels in their natural, byssally attached state. Mussels attached with byssal threads within a flume for 24 hours in no flow (0 m/s) and then were subjected to water velocities of 0, 0.5, 1.0 and 1.8 m/s for 8 hours. We determined the percentage of the mussels that dislodged in flow at each velocity and the resistance force required to mechanically detach mussels in shear and tension after 32 hours of attachment in no flow. We used an inverse LRFD method to calculate lift and drag coefficients from the hydrodynamic load that must have been imposed on a mussel in flow to yield the observed percentage dislodgment. Thus far, our inverse LRFD method yielded lift coefficients that were roughly 2 times higher for quagga than for zebra mussels. These lift coefficients were 2 to 4 times higher than those of other species of mussels in which lift force was measured directly on artificially attached mussels. The higher lift coefficients that we calculated for zebra and quagga mussels might have resulted from different boundary conditions of byssally relative to artificially attached mussels. Our inverse LRFD method was useful in determining lift and drag coefficients of mussels attached under natural conditions and demonstrated novel fluid dynamics that might influence their colonization of new habitats.
