Consider the flow field over a circular cylinder mounted perpendicular to the

Consider the flow field over a circular cylinder mounted perpendicular to the flow in the test section of a low-speed subsonic wind tunnel. At standard sea level conditions, if the flow velocity at some region of the flow field exceeds about 250 mi/h, compressibility begins to have an effect in that region. Calculate the velocity of the flow in the test section of the wind tunnel above which compressibility effects begin to become important, i.e., above which we cannot accurately assume totally incompressible flow over the cylinder for the wind tunnel tests.