Quote:
Originally Posted by Hersbird
The problem is his scale on the Ram and the Ford is silly small, it's like he modeled a toy car and is running that without changing the dimensions. Doesn't a smaller, shorter car make it more difficult for air to reattach? By making the Ram and Ford toy sized wouldn't that give them disproportionately high Cd numbers in the comparison?[/url]
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Yes. If he really didn't adjust the size (it looks like the dimensions are 1/10 what they should be), that will throw off the Reynolds number, which is proportional to length, and you won't get an accurate modeling of the airflow over the real truck unless you increase fluid speed to compensate.