To import the csv file:
tubeArbitrary = Import["tube_arbitrary.csv", "HeaderLines" -> 1];
To extract the x and y, each in a separate list:
XtubeArbitrary = tubeArbitrary[[All, 1]];
YtubeArbitrary = tubeArbitrary[[All, 2]];
To extract x and y and U velocity in z direction in a single data-set:
XYUtubeArbitrary = tubeArbitrary[[All, {1, 2, 6}]];
To plot the geometry based on the (x,y) points:
ListPlot[Thread[{XtubeArbitrary, YtubeArbitrary}], PlotRange -> Automatic, AspectRatio -> Automatic];
To contourplot it:
ListContourPlot[XYUtubeArbitrary, Contours -> 500, ColorFunction -> "Rainbow", ContourStyle -> None, AspectRatio -> Automatic, PlotLegends -> Automatic];