Reply To: For analysis of flow over cylinder or sphere in 2D- How does ANSYS knows it’s sphere or cylinder.

[Rob]

In the theory what governs the heat generation in the cylinder/sphere? In Fluent you're setting an external HTC and temperature and then Fluent will pull heat from that based on near wall conditions.
The 2d surface area assumes the cylinder is 1m long.
Lift and drag are forces, the coefficients rely on reference values: read the definitions to make sure you understand what you're reporting.
Finally, check the mesh and ensure you have a very well resolved near cylinder mesh (y+ is the cell height, you need to resolve circumferentially too).