I have imported some CFD results (in csv format) into Mathematica to do some further processing of the data.

One of my 2D geometries is as:

Now, when I try to do the contour plot, I get the following:

Why is contour plot filling those areas above and below the narrow section with purplish color. Those regions are not even within my X and Y coordinates (see the image for geometry above)?

Any ideas?

Thanks

Cross-posted here. I am attaching a sample of my data (a csv file for the above geometry). Note that I am only working with columns 1 and 2 (as x and y) and column 6, as my velocity in z direction.