Schematic of the experimental setup for the observation of CNT deflections, due to fluid flow, by (i) monitoring the transmitted laser intensity variations and by (ii) CCD imaging. The insets illustrate the orientation of the CNT mats with respect to incident laser illumination.
(a) The in situ shearing of CNT mats, as observed through SEM imaging, can be quite accurately modeled as through the deflection of a cantilever (as depicted by the outlines). (b) The calibration of the transmitted laser intensity was done by monitoring the transmission through CNT patterns arranged in a and a pattern, respectively. An excellent agreement with predicted values, based on CNT coverage, was observed. (c) Modeling the effect of fluid flow on aligned CNT mats with a superposed circular laser spot. On exposure to fluid flow, the CNT displacement is correlated with a measured variation in the laser transmission intensity and measured by a photodetector or monitored through CCD imaging.
The variations in the transmitted laser intensity, through the CNT mats exposed to varying fluid velocities (i.e., 5, 16, 22, 31, 41, and 27 m/s), as a function of time. The robustness of the measurements is revealed in the digital response to various fluid velocities and return to a reference value when the flow is removed.
(a) Simulations of boundary layer thickness as a function of CNT distance from the leading edge of the substrate for fluid velocities of 10 and 30 m/s. (b) Simulations of nanotube deflections for velocities of 10 and 30 m/s, for CNTs away from the leading edge.
(a) The deflections of CNT mats, obtained through monitoring the transmitted laser intensity, as a function of air velocity, for five different samples. Numerical simulation was used to fit the , which is . (b) The corresponding measurements of the deflections through CCD imaging yielded an .
The CNT mat ( array) deflections were seen to be a function of both the nature of the fluid used (i.e., argon and air) and fluid velocity. We saw that by scaling the CNT deflections, subject to air, with the ratio of the argon density and air density , the behavior of CNT samples in air can be very accurately predicted (as indicated by the argon predicted). The is .
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