Some years ago, Peter Wright wrote an article (maybe for Racecar Engineering) in which he described in some detail, and with the clarity so typical of him, the instrumentation used in the wind tunnel testing of F1 cars. Drag and down forces are naturally measured, among other parameters.
He also mentioned that, as seems logical, compressed air is piped to the model exhaust tailpipes, to simulate the flow of exhaust gases, which have a considerable influence, as is widely known.
I have been wondering how the drag of the radiators and oil coolers is simulated, as the flow from the exits, near the rear of the car, must obviously be affected by this, in turn affecting the total flow pattern. Such simulation must naturally be based on values already known, or estimated, for these items, as installed in ducts similar in shape and size to those intended for the car. Anyone have any knowledge of this matter?