https://www.sciencedirect.com/search?qs=Local%20Nusselt%20Number%20past%20a%20Heated%20elliptic%20cylinder&show=25&sortBy=relevance

I would recommend to use CFD-Post instead of native Fluent postprocessing. In CFD-Post you can cut your elliptic cylinder with an orthogonal plane, which results in a Polyline constructed from boundary intersection of your cylinder and the cutting plane. Along that Polyline you can display a Chart of any primary variable or derived expression. If you now write a CFD-Post expression, which gives you the angle as a function of (x,y) coordinates along this polyline you have won the game, since you can use this expression as primary axis of your chart. Nonetheless to say, that you can export the values along that Polyline in CSV format e.g. to MS Excel for a better chart formatting (e.g. for publication purposes). Potentially you would like to separate the 2 different Nu curves along upper and lower surface of your elliptic cylinder by discriminating by the sign of your vertical coordinate, otherwise both are plotted together in one diagram.