In a given 2-D geometry, which area does fluent considers for the calculation of Drag Coefficient? I am solving for the drag of an ellipse. Fluent gives the value of Drag Coefficient directly. But how do we know the area considered by fluent?

The area is simply the cross sectional area of a sphere, pi*r^2

Projected area is used in finding lift and drag coeffiecient. For example, you can give the diameter of cylinder when you are interested in flow over cylinder.

I was trying to mach the coeffient of drag value calculated by fluent with my mannual calculation, but the values were different. But Later I found that fluent takes some default vale of Area and other parameters. It does not consider the Area in our geometry.