. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. -25 -20 -15 -10 -50 5 10 15 20 25 Angle of Incidence (degrees) Figure 7. Angle-specific flux from a flow-protected blade at Re, = 2700. Open circles show the static response of the model; filled circles, the dynamic response. The vertical bars are the standard deviation of measure- ments among seven cycles, an index of the intensity of turbulent mixing over the model. (A) Crest. (B) Trough. The arrows indicate the order in which angles were achieved during a cycle of pitching. The pattern of flux at Re, = 2700 for the flow-e
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. -25 -20 -15 -10 -50 5 10 15 20 25 Angle of Incidence (degrees) Figure 7. Angle-specific flux from a flow-protected blade at Re, = 2700. Open circles show the static response of the model; filled circles, the dynamic response. The vertical bars are the standard deviation of measure- ments among seven cycles, an index of the intensity of turbulent mixing over the model. (A) Crest. (B) Trough. The arrows indicate the order in which angles were achieved during a cycle of pitching. The pattern of flux at Re, = 2700 for the flow-exposed blade is more complex than that of the other models (Fig. 8). Static flux (open circles) is very low when the blade is parallel to flow (lower than the small-angle values for either the plate or the flow-protected blade), but increases with increasingly positive angle of pitch to values higher than those for the other models. (The surface temperature during this series of measurements was 8% higher than the com- parable measurements for the flow-protected blade, but this difference in temperature differential between surface and ambient temperature is not sufficient to account for the difference in flux between models.) The standard deviation of flux to the flow-exposed model is relatively small at positive angles, indicative of suppressed turbulence. Static flux initially increases steeply with increasingly negative pitch angle (again to values high relative to the other mod- els!, but reaches a peak at about —15°, decreasing sharply thereafter. This decrease in flux at extreme negative angles is associated with an increase in standard deviation. An explanation for this anomalous negative correlation between flux and turbulence at high negative angles is not readily apparent. It should be kept in mind, however, that the width of this blade is small relative to its length, and as a conse- quence there is substantial potential for three-dimensional flow in the vicinity
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
