I want to carry out CFD of a cylinder. Re is around 9.51x10^5 . I made a 2D circle on CATIA. Next, I have to define the test section's physical boundaries. How big should the test section (box in figure below) be? What should be the position of the cylinder in this test section (box in figure below)? Note: The picture below doesn't show my CFD. It has only been attached for reference to the test section.