Changes between Version 19 and Version 20 of Tutorial/AdvancedParticleImagingVelocimetry


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Timestamp:
Jan 23, 2015, 10:04:35 PM (6 years ago)
Author:
sommeria
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  • Tutorial/AdvancedParticleImagingVelocimetry

    v19 v20  
    55
    66== Visual check ==
    7 Launch the GUI '''uvmat''' and open an image in  /UVMAT_DEMO_FILES/CONVECTION/Dalsa1, for instance 'Dalsa1_100_1.png'. It represents a convection experiment in a box with rectangular vertical cross section, with a heated right hand vertical wall. A plume with small lateral extension is produced near this wall which is a source of difficulty for PIV.  As ususal the first step is a visual observation of the particle motion. Zoom the image on the right hand side and press the button '''movie_pair''', to see the displacement from image index _100_1 to _100_2. We can compare the influence of time interval by selecting the j index pairs 1-2 (100 ms), 2-3 (200 ms) or 1-3 (300 ms). We can notice that the pair 1-3 is needed to clearly see the motion in the interior while it is too large for the displacement in the plume.  The smaller interval 1-2 is then appropriate.
     7Launch the GUI '''uvmat''' and open an image in ''UVMAT_DEMO03_PIVchallenge_2005C/images'' , which represents a jet (images from PIV challenge, ref...). Images are organized in pairs, denoted with labels a, b with a short time interval  Dt=0.01 ms, with interval 2 ms between two successive pairs. The timing and geometric calibration has been provided in the xml file images.xml, in the same way as discussed in section .. for a single pair.
     8
     9check the image pair between a and b, then between 1 and 2, dt is displayed while the time is displayed in the upper right edit box.
     10
     11'''Civ: i'''mport the parameters stored in ...
     12
     13small displacement of the order of 1 pixel, so small search box.
     14
     15Check filter, compare filter2 and civ2, make transverse cut...
     16
     17'''merge proj: '''
     18
     19define a physical grid for the final results, select (U,V0 and curl , div, use ProjMode =interp_tps
     20
     21launch merge_proj: results are obtained as 2D matrices, open with uvmat. Select U in get_field.
     22
     23No info left on the PIV process after projection. This is the start for the scientific analysis.
     24
     25'''time_series:'''
     26
     27'''turb_stat:'''
     28
     29It represents a convection experiment in a box with rectangular vertical cross section, with a heated right hand vertical wall. A plume with small lateral extension is produced near this wall which is a source of difficulty for PIV.  As ususal the first step is a visual observation of the particle motion. Zoom the image on the right hand side and press the button '''movie_pair''', to see the displacement from image index _100_1 to _100_2. We can compare the influence of time interval by selecting the j index pairs 1-2 (100 ms), 2-3 (200 ms) or 1-3 (300 ms). We can notice that the pair 1-3 is needed to clearly see the motion in the interior while it is too large for the displacement in the plume.  The smaller interval 1-2 is then appropriate.
    830
    931== Geometric calibration ==
     
    2143
    2244== Visualizing  the velocity fields ==
    23 '''** Vectors''' 
     45'''** Vectors'''
    2446
    2547To read the velocity field, open it with the GUI  ''''uvmat''''. Velocity vectors are displayed in the central window, while the histograms of each component are in the lower left windows, see Fig. [uvmat_fig]. The arrow length is automatically set by default. It can be adjusted by the edit box '''[!VecScale]''' in the  frame '''[Vectors']''' on the right hand side.
     
    3254
    3355== Derived fields ==
    34 Other field representations are available, selected in the menu '''[Fields]''' at the top of the GUI. For instance the option 'u' provides a (false) color map of the x wise velocity component. A contour plot can be obtained instead of a color map by selecting the option 'contour' in the menu '''[!ListContour]''' in the frame''' [Scalar] '''. Then select the contour interval, for instance 0.5. The result is shown in the following figure. 
     56Other field representations are available, selected in the menu '''[Fields]''' at the top of the GUI. For instance the option 'u' provides a (false) color map of the x wise velocity component. A contour plot can be obtained instead of a color map by selecting the option 'contour' in the menu '''[!ListContour]''' in the frame''' [Scalar] '''. Then select the contour interval, for instance 0.5. The result is shown in the following figure.
    3557
    3658<doc145|center>