What is the best way to perform a simulation on Curved Surface or a Fillet, Its a good practice to remove curved surface as a part of pre-processing but the main reason of the of Curved surface is to distribute stresses rather concentrating stresses on a particular region, Can I use a fine mesh at the Curved surface and at the fillets Instead of completely removing the Curved surfaces.
Nowadays I would recommend leaving the fillets. On modern hardware you can solve problems in millions of degrees of freedom without issue. With sharp reentrant corners you will end up with singular stresses that are more troublesome evaluate. With any real radius and enough mesh refinement, you should be able to converge on real stresses.
Curvature Based Mesh automatically does some refinement in these areas. If it is generating too much refinements in areas you don't need, just increase the minimum element size.
Energy Norm Error plots are also a useful tool to be able to identify areas that need additional mesh refinements: https://hawkridgesys.com/blog/solidworks-simulation-energy-norm-error-plots
Then go in and place Mesh Controls to refine those areas until you see the stress levels level off or "converge"
Depending on your setup, you can also use adaptive meshing to automatically perform iterations of mesh refinement.
You can use a very fine mesh.
The problem is, the mesh create triangles which will have 3 sharp edges.
You'll never get rid of the stress concentration.