1 Overview 2 Details of the Model Construction - Canada France ...

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Figure 13: Still frames of boundary layer visualization experiment with probe B6 set at a 50 mm height above the terrain. Side view (left) is looking due north and the top view is shown on the right. Variations in dye contrast are due to the effect of the varying flow speed at fixed dye injection rate (the dye is more diffuse at the higher velocities). The top view images (right) have been processed to improve the contrast of the blue dye.
dye probe was held near each vent location to visualize the entrainment of dye towards and into the unvented dome model. 8.4 Turbulence Generator Investigation Robert Breidenthal suggested that if we wished to increase the level of turbulent layer up to the level of the dome that we could install some turbulence generators upwind of the dome. In practice this is unlikely to be feasible, however to give this idea a try we cut a sawtooth shaped turbulence generator board out of corrugated plastic poster-board with teeth 38 mm tall and 19 mm wide at the base. This structure was held on the upstream edge of the model base plate and the flow was visualized using dye probe B6. The depth of the turbulence generator in the water was varied to determine at what point it had an effect on the vortex on the upstream side of the observatory base. The turbulence generator board is shown in Figure 15. 9 Basic Data Product The files were saved in the AVCHD Lite format of the Panasonic ZS7 cameras. There were a few issues around using the files in this format. For one, the AVCHD format is not commonly supported by older video display software; this is a fairly easy problem to work around. Secondly, we wished to use MATLAB to automatically process the video to determine the flushing times in a more quantitative way, however this video format is not supported by MATLAB. Thirdly, the 720p HD format video was unnecessarily large for most common use and precluded easy distribution on inexpensive data media (e.g. DVD disks). The video files were first renamed and organized in a self-explanatory and intuitive path structure that makes it easy to navigate to the video pertaining to a specific experimental configuration. These files were then converted using the SUPER video conversion tool to a AVI format using the following settings: • Format: AVI • Output video codec: DivX • Output audio codec: mp3 • Video scale size: 640 x 360 pixels • Frame per sec: 14.985 Hz • Bitrate: 9600 kbps • Options: Hi-quality • Audio: 1 Channel, 22050 Hz sampling, 96 kbps bitrate • MEncoder and DirectShow decode selected (the latter only works for the Windows OS). Down-conversion from the nominal 60 Hz (30 Hz actual!) frame rate to 15 Hz was necessary to ensure normal playback speed of the video. Conversion to the actual 30 Hz frame rate of the video resulted in video that played back at approximately twice the correct speed; this was found for at least 4 conversion packages tried. This problem is related to the decoders of the AVCHD Lite format ignoring a bit that indicates that each 30 Hz frame should be played twice to achieve the nominal 60 Hz playback.
Page 1 and 2: Canada-France-Hawaii Telescope Corp
Page 3 and 4: Figure 3: Vent dimensions in inches
Page 5 and 6: Figure 6: View through the shutter
Page 7 and 8: 4 Dye Probe Locations Dye probe por
Page 9 and 10: gradually narrows down over a lengt
Page 11 and 12: 6.3 Video capture Two Panasonic Lum
Page 13: 4. Windscreen position (3): Either
Page 17 and 18: 10 Lessons learned • A dome shutt
Page 19 and 20: Figure 17: Path structure used to o
Page 21 and 22: 11 University of Washington 36” W
Page 23 and 24: Note: at the expected operating win
Page 25 and 26: ing everything needed. • It takes

1 Overview 2 Details of the Model Construction - Canada France ...

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