. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FLOW-INDUCED FORCES IN ALGAL CANOPIES 129 Reconfiguration in //(in- Flexible structures such us algae reconfigure in flow as velocity increases such that their relative drag is reduced at higher flow speeds. For solitary thalli, a useful measure of velocity-dependent relative drag reduction is the E-value (Vogel, 1984). which quantities this relative reduction in drag ( the decrease in C „ with increase in velocity). D IT- (2) where D = drag at a particular flow speed (U). A value for E is determined as the slope of a l
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FLOW-INDUCED FORCES IN ALGAL CANOPIES 129 Reconfiguration in //(in- Flexible structures such us algae reconfigure in flow as velocity increases such that their relative drag is reduced at higher flow speeds. For solitary thalli, a useful measure of velocity-dependent relative drag reduction is the E-value (Vogel, 1984). which quantities this relative reduction in drag ( the decrease in C „ with increase in velocity). D IT- (2) where D = drag at a particular flow speed (U). A value for E is determined as the slope of a linear regression of log (D/U~) versus log U for regions of this graph without inflection points: KE is the antilog of the intercept of this line. The magnitude of E is zero for a structure, such as a rigid sphere, that does not reconfigure in flow. The steeper the negative slope (, the greater the absolute value of the negative slope), the greater the relative drag reduction ex- perienced with an increase in velocity as a consequence of reconfiguration. E and KE were determined for the same eight solitary thalli of C. crispus for which the CD was quantified (de- scribed above). Canopy experiments For all treatments in the canopy experiments, force ex- erted by one thallus (mass = g. planform area = m ) on the force beam was determined at flow speeds of , , and m s"1. All measurements were repeated three times (sufficient sampling given the low variance observed). All statistical comparisons between treatments, using ANOVA, are for force determined at the highest experimental flow speed ( m s '). Scheffe /•"-tests were used for a posteriori comparisons between treatments. At all experimental velocities and for all treatments, forces on the stipe of the experimental thallus were quan- tified when it was m long (, only half the length of the stipe protruded into flow, which was the same as the length of the stipes of
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
