The effects of inlet conditions on downstream mixing in turbulent pipe flow have been studied with the use of photoactivatable fluorophores and standard laser-induced fluorescence techniques. The different inlet conditions included both geometry changes and changes in the manner in which the constituents were introduced into the flow. Results indicate that small changes in inlet geometry can greatly affect the downstream mixing rate. Changes in the geometry of the inlet had a greater influence on downstream mixing than did the manner in which constituents were introduced into the flow. Further experiments included a static mixer that was used in conjunction with two different inlet conditions. It was found that the inlet condition greatly affects the effectiveness of the static mixer. The static mixer is most effective when placed downstream of an inlet that produces scalar length scales that are similar in size to the elements in the mixer (i.e., the pipe diameter). Overall, the results of these experiments demonstrate that the method used to introduce two constituents to be mixed in pipe flow can profoundly affect the downstream mixing rate.

Efficient processing of visual information is crucial to safe driving. Previous research has demonstrated that driving experience strongly affects attentional allocation, with large differences between novice and experienced drivers. Expanding on this, we explored the influence of non-driving experiences on attentional allocation by comparing drivers with and without cycling experience. Based on situation awareness field studies, we predicted cyclist-drivers would demonstrate superior performance. Participants were 42 experienced drivers (17 female, 25 male) aged 30-50 years (M=39.8): 20 drivers and 22 cyclist-drivers. The experiment used a change detection flicker task, in which participants must determine whether two alternating images are identical (change-absent) or differ in a single detail (change-present). The changed object was either a road sign, car, pedestrian, or bicycle. Change target significantly affected both accuracy and response time: all participants were slower and less accurate at detecting changes to road signs, compared with when the change was a moving road user (i.e., car, pedestrian, bicycle). Accuracy did not differ significantly between groups, but cyclist-drivers were significantly faster than drivers at identifying changes, with the effect being largest for bicycle and sign changes. The results suggest that cycling experience is associated with more efficient attentional processing for road scenes.

Despite its use in numerous industrial applications, the specific mechanisms governing mixing in pipe flow are not fully understood. Recent experiments by Guilkey et al. (1997) indicate that simple changes in the geometry of the inlet at which the scalar is introduced can lead to substantial differences in the rate of scalar variance decay downstream. In an effort to better understand this phenomenon, the effects of two different initial conditions on mixing in turbulent pipe flow were investigated. The present results are compared with three earlier turbulent mixing experiments. Overall, the results of these experiments demonstrate that the method used to introduce two constituents to be mixed in pipe flow can profoundly affect the downstream mixing rate.