Visualizing Hairpin Vortices in Turbulence

This summer I worked at the Univeristy of Minnesota at Minneapolis under the direction of Victoria Interrante. I joined one of Vicki's continuing research projects which is a joint project with the aerospace department. The purpose of the project was to visualize the properties of hairpin vortices over the surface of a wind tunnel. Since this has been an ongoing project, the goal was to improve the previous version of code and add a user interface.

The main focus of my job was to create a user interface. My first step involved learning how to use MUI, a OpenGL toolkit for C programming. After installing MUI and creating a few buttons I was well on my way of developing a user-friendly interface. Some of the features I included allow the user to specify what measurements should be displayed and how they want to display them.

The following is a view of the interface displaying the vorticity buttons and the resulting visualization:

Vorticity Buttons
Output As you can see, a single color (green) is used to visualize the velocity patches. The settings show the strength of the velocity at each point in the patch as the low vorticity gradually increases towards the center of the patch. This view allows the user to get a good overall view of the vorticity and surrounding velocity patches in addition to the scanning function (pink) in the attempt to see if a neighboring patch is really a continuation of the same hairpin structure.

These next figures display a different option involving the same vortices patches. The pixels between different breakpoints are well defined.

Vorticity Buttons
I also included a graphical view of each measurement to make the breakpoint values more interactive by allowing the user to drag the breakpoints with the mouse. The colored labels of each breakpoint correspond to the patches in the visualizations:

Breakpoint Graph

On top of the interface I made the program event-driven as opposed to the previous version where there was no input from the user. The program is documented and there are comments in the code so that future project members will be able to further develop the program with ease.

Due to time constraints I was not able to complete a few options for displaying certain measurements. It would also be nice to develop a better way to decide wether or not to display the marker on each swirl or Reynold Shear Stress patch. A large amount of time was spent attempting to find the cause of an irregular segmentation fault which is yet to be resolved.

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