TABLE OF CONTENTS Various methods for flow imaging have been proposed and are described in this section. The flow imaging can be used for measuring the fluid flow velocity or to take snapshots of the fluid flow to visualize flow profiles or eddies. With some techniques it can be used to follow the motion of fluids within a silicon chip, for example, to show the droplet formation within an inkjet printer nozzle [104] or the spinning of a microrotor [105]. For true flow velocity measurement, the flow imaging technique is rather expensive due to high equipment costs and the requirement of extensive computation. Therefore, it may only be used for specialized applications, where not only the flow velocity but also the flow profile is of interest. For measured flow range data of the various techniques, see Table 9.13.
| Author; Year | Flow Range | Fluid |
|---|---|---|
| Leu et al. [104]; 1997 | 4 8 nl/s |
|
| Han et al. [105]; 2002 | 250 ?m/s to 62 mm/s | Water |
| Chetelat et al. [106]; 2002 | 1 m/s | Water |
| 10 m/s | Air | |
| Shelby et al. [107]; 2003 | 47 m/s |
|
The technique published by Leu et al. [104] measures steady-state flow in micropipes of various shapes by way of illustration. The experimental setup includes a wide bandwidth X-ray monochromator and a high frame rate CCD camera (160 frames/sec). Flow image sequences were collected for micropipes of 100-to 400- ?m diameter. A flow recovery algorithm derived from fluid...
