Changes between Version 69 and Version 70 of WikiStart


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Timestamp:
Oct 23, 2017, 2:55:16 PM (3 years ago)
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steiger5na
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    4444
    4545== 2.3.2 Reference axis for ice front experiments ==
    46 By definition we will use Ox and Oy axis to define the along channel and cross channel axis. The central reference point (0,0) is chosen to be at the front of the ice shelf and in the middle of the channel. Positive u - direction corresponds to the flow direction towards the ice shelf and positive v - direction is directed to the "west".
    47 
    48 
     46By definition we will use Ox and Oy axis to define the along channel and cross channel axis. The central reference point (0,0) is chosen to be at the front of the ice shelf and in the middle of the channel. Positive u - direction corresponds to the flow direction towards the ice shelf and positive v - direction is directed to the "west".
    4947
    5048== 2.4 References axis along the wall (horizontal and vertical) - Nadine add image! ==
     
    9997'''Conductivity Sondes (CS)'''
    10098
    101 '''Particle Imaging Velocimetry (PIV)''' A Spectra-Physics Millennia ProS 6W YAG continuous laser (532 nm) in conjunction with 2 cameras was used to provide PIV images. The laser light sheet was brought in parallel to the bottom of the tank in case of the slope front experiments and tilted by 2% to match the slope of the channel in case of the ice front experiments. The light sheet can then be racked in the vertical through a series of steps through the use of a motorized traverse and a mirror set at 45 degrees. The laser has another set of optics to point the light sheet down at the mirror, producing the light sheet. The laser light sheet positions are then synchronized with the PIV cameras. The laser light sheets cover the whole topography, but are slighlty bended towards the sides, so that they are closer to the bottom at the source and at the end of the topography compared to the middle. Also a vertical laser was used together with a vertical camera to observe the flow in a cross section. The three PIV cameras consist of:
    102 - one Falcon1 camera ''(Falcon 4M, CMOS 2432*1728 pixels, 10 bits)'' as the vertical camera – with a 35 mm objective lens.[[BR]]
     99'''Particle Imaging Velocimetry (PIV)''' A Spectra-Physics Millennia ProS 6W YAG continuous laser (532 nm) in conjunction with 2 cameras was used to provide PIV images. The laser light sheet was brought in parallel to the bottom of the tank in case of the slope front experiments and tilted by 2% to match the slope of the channel in case of the ice front experiments. The light sheet can then be racked in the vertical through a series of steps through the use of a motorized traverse and a mirror set at 45 degrees. The laser has another set of optics to point the light sheet down at the mirror, producing the light sheet. The laser light sheet positions are then synchronized with the PIV cameras. The laser light sheets cover the whole topography, but are slighlty bended towards the sides, so that they are closer to the bottom at the source and at the end of the topography compared to the middle. Also a vertical laser was used together with a vertical camera to observe the flow in a cross section. The three PIV cameras consist of: - one Falcon1 camera ''(Falcon 4M, CMOS 2432*1728 pixels, 10 bits)'' as the vertical camera – with a 35 mm objective lens.[[BR]]
    103100
    104101- PCO1 (PCO.edge5.5 CMOS cameras (2560*2160 pixels)) with a 35 mm objective lens overlooking the part in front of the source in the slope front experiments and the ice shelf in the ice front experiments.[[BR]]
     
    106103- PCO2 (PCO.edge5.5 CMOS cameras (2560*2160 pixels)) with 20 mm objective lens overlooking the continental self and trough in the slope front experiments and the channel in the ice front experiments.[[BR]]
    107104
    108 After experiment 26 of the slope front expriments, 60 micron particles were used for the flow seeding. The number of slices were adjusted to the need of the experiment and is listed in the file LIST_OF_EXPERIMENTS.xlxs. The number of slices, dt between the images, exposure time (either 20-50), the number of images and the number of scans had to be decided before each experiments. The slope front experiments also contained series of images at one horizontal slice to better observe the evolution of the flow. The vertical laser was turned on after a steady flow was established/ at the end of the experiment. 
     105After experiment 26 of the slope front expriments, 60 micron particles were used for the flow seeding. The number of slices were adjusted to the need of the experiment and is listed in the file LIST_OF_EXPERIMENTS.xlxs. The number of slices, dt between the images, exposure time (either 20-50), the number of images and the number of scans had to be decided before each experiments. The slope front experiments also contained series of images at one horizontal slice to better observe the evolution of the flow. The vertical laser was turned on after a steady flow was established/ at the end of the experiment.
    109106
    110107During horizontal PIV, the vertical camera was turned on (with the same acquisition as the PCO1 and PCO2) to produce an .xml file that contains information on the time, dt, exposure time, times for the scanning. During some experiments, this .xml file was missing (technical mistake or if we stopped the acquisition before it was done), so that .xml files from other experiments have to be used and modified to fit the setup. However, the starting time is not correct then.
    111 
    112108
    113109== 3.2 Definition of time origin and instrument synchronisation ==
     
    141137For the vertical calibration the images are saved in a different file format with extension '.seq'. The format can be changed in the UVMAT software, but the folder with the vertical images should not be renamed (e.g. '2017-09-08T16.04.32'). To change the image format, choose RUN -> Field Series. Chose the right input file, an select 'extract_rdvision.m', click INPUT and RUN. The image will be saved in a new folder as a .png file and is ready for use in UVMAT.
    142138
    143 ===Laser sheet calibration===
    144 ==Slope front experiments==
    145 ||Laser setting||$H_{real}||||
     139=== Laser sheet calibration ===
     140== Slope front experiments ==
     141||Laser setting||$H_{real}||
    146142||650||55 cm||
    147143||700||49.5 cm||
     
    150146||900||30 cm||
    151147
    152 ==Ice front experiments==
    153 
    154 
     148== Ice front experiments ==
     149||Laser setting||$H_{real}$||
     150||50||14 cm||
     151||200||26 cm||
     152||300||35 cm||
     153||500||45 cm||
     154||600||53 cm||
     155||700||70 cm||
     156||800||79 cm||
     157||850||85 cm||
    155158
    156159=== Probes calibration ===