To read the velocity field, open it with the 'uvmat' interface. It has been written as a file with a '.nc' extension (netcdf file format) in the subdirectory 'A', set in the 'civ' interface. Velocity vectors are displayed in the central window, while the histograms of each component are in the right windows, see Fig. 1. The arrow length can be adjusted by unselecting the option 'auto' on the top, and changing the value in the edit box 'max', and pressing the RUN '0' red button to get the new display.
The vector color indicates the quality of the image correlation maximum leading to each vector, blue is excellent, green average, red poor. The thresholds for such color display can be adjusted by the upper right sliders, from 0 to 1 (perfect image correlation).
The position (x,y) and velocity components (u,v) can be displayed for each vector by pressing the button 'select' on the upper right, and selecting the vector with the mouse cursor. A line can be drawn with the mouse by pressing the button 'set_line', and the transverse and longitudinal velocity components along this line plotted (on a separate graph figure) by pressing the RUN '0' button.
You can superpose the images and velocity field by visualizing first the image, then selecting the check box '-' at the left of the file name (the image name is then duplicated in the second edit box), then selecting 'velocity' in the 'FIELDS' menu.
To get the vorticity field and other spatial derivatives, come back to the CIV menu, select the 'patch1' check box alone, and press 'RUN', which will produce an interpolated velocity field and their spatial derivatives. Vorticity can be visualized in the 'uvmat' interface, selecting 'vort' in the 'FIELDS' menu. The color code can be adjusted by unselecting the option 'auto' on the top, and adjust the 'min' (blue) and 'max' (red) values.
To eliminate the spurious data outside the fluid boundaries, select the check box 'mask'. The mask has been stored as a mask image file 'UV_DEMO/EX_1/frame1_mask_1.png'.