Optimization of small elements of construction
 

I am optimizing aerodynamic of small element of car in Star-CCM+.
I have several parameters defining it's geometry.
As it is necessary carry out a series of calculations, important to minimize the run time.

I have few suggestions:

1) Carry out one calculation of car aerodynamic then consider only small space around element. Use calculated velocity field as boundary for reduced space.
2) Carry out many calculations with different parameters and rough calculation grid then choose few best results and recalculate them at grid with more elements.

How can I do that? What features of Star-CCM+ should I use?

I think specially your second strategy is very good. you can start with a coarse mesh ( element) and then by finding the proper physics, refine the mesh and run the simulation again. It can be done by changing the reference value of the mesh.